Merge branch 'ks/fix-rebase-doc-picture'
[git/git.git] / Documentation / git-rebase.txt
1 git-rebase(1)
2 =============
3
4 NAME
5 ----
6 git-rebase - Reapply commits on top of another base tip
7
8 SYNOPSIS
9 --------
10 [verse]
11 'git rebase' [-i | --interactive] [options] [--exec <cmd>] [--onto <newbase>]
12 [<upstream> [<branch>]]
13 'git rebase' [-i | --interactive] [options] [--exec <cmd>] [--onto <newbase>]
14 --root [<branch>]
15 'git rebase' --continue | --skip | --abort | --quit | --edit-todo
16
17 DESCRIPTION
18 -----------
19 If <branch> is specified, 'git rebase' will perform an automatic
20 `git checkout <branch>` before doing anything else. Otherwise
21 it remains on the current branch.
22
23 If <upstream> is not specified, the upstream configured in
24 branch.<name>.remote and branch.<name>.merge options will be used (see
25 linkgit:git-config[1] for details) and the `--fork-point` option is
26 assumed. If you are currently not on any branch or if the current
27 branch does not have a configured upstream, the rebase will abort.
28
29 All changes made by commits in the current branch but that are not
30 in <upstream> are saved to a temporary area. This is the same set
31 of commits that would be shown by `git log <upstream>..HEAD`; or by
32 `git log 'fork_point'..HEAD`, if `--fork-point` is active (see the
33 description on `--fork-point` below); or by `git log HEAD`, if the
34 `--root` option is specified.
35
36 The current branch is reset to <upstream>, or <newbase> if the
37 --onto option was supplied. This has the exact same effect as
38 `git reset --hard <upstream>` (or <newbase>). ORIG_HEAD is set
39 to point at the tip of the branch before the reset.
40
41 The commits that were previously saved into the temporary area are
42 then reapplied to the current branch, one by one, in order. Note that
43 any commits in HEAD which introduce the same textual changes as a commit
44 in HEAD..<upstream> are omitted (i.e., a patch already accepted upstream
45 with a different commit message or timestamp will be skipped).
46
47 It is possible that a merge failure will prevent this process from being
48 completely automatic. You will have to resolve any such merge failure
49 and run `git rebase --continue`. Another option is to bypass the commit
50 that caused the merge failure with `git rebase --skip`. To check out the
51 original <branch> and remove the .git/rebase-apply working files, use the
52 command `git rebase --abort` instead.
53
54 Assume the following history exists and the current branch is "topic":
55
56 ------------
57 A---B---C topic
58 /
59 D---E---F---G master
60 ------------
61
62 From this point, the result of either of the following commands:
63
64
65 git rebase master
66 git rebase master topic
67
68 would be:
69
70 ------------
71 A'--B'--C' topic
72 /
73 D---E---F---G master
74 ------------
75
76 *NOTE:* The latter form is just a short-hand of `git checkout topic`
77 followed by `git rebase master`. When rebase exits `topic` will
78 remain the checked-out branch.
79
80 If the upstream branch already contains a change you have made (e.g.,
81 because you mailed a patch which was applied upstream), then that commit
82 will be skipped. For example, running `git rebase master` on the
83 following history (in which `A'` and `A` introduce the same set of changes,
84 but have different committer information):
85
86 ------------
87 A---B---C topic
88 /
89 D---E---A'---F master
90 ------------
91
92 will result in:
93
94 ------------
95 B'---C' topic
96 /
97 D---E---A'---F master
98 ------------
99
100 Here is how you would transplant a topic branch based on one
101 branch to another, to pretend that you forked the topic branch
102 from the latter branch, using `rebase --onto`.
103
104 First let's assume your 'topic' is based on branch 'next'.
105 For example, a feature developed in 'topic' depends on some
106 functionality which is found in 'next'.
107
108 ------------
109 o---o---o---o---o master
110 \
111 o---o---o---o---o next
112 \
113 o---o---o topic
114 ------------
115
116 We want to make 'topic' forked from branch 'master'; for example,
117 because the functionality on which 'topic' depends was merged into the
118 more stable 'master' branch. We want our tree to look like this:
119
120 ------------
121 o---o---o---o---o master
122 | \
123 | o'--o'--o' topic
124 \
125 o---o---o---o---o next
126 ------------
127
128 We can get this using the following command:
129
130 git rebase --onto master next topic
131
132
133 Another example of --onto option is to rebase part of a
134 branch. If we have the following situation:
135
136 ------------
137 H---I---J topicB
138 /
139 E---F---G topicA
140 /
141 A---B---C---D master
142 ------------
143
144 then the command
145
146 git rebase --onto master topicA topicB
147
148 would result in:
149
150 ------------
151 H'--I'--J' topicB
152 /
153 | E---F---G topicA
154 |/
155 A---B---C---D master
156 ------------
157
158 This is useful when topicB does not depend on topicA.
159
160 A range of commits could also be removed with rebase. If we have
161 the following situation:
162
163 ------------
164 E---F---G---H---I---J topicA
165 ------------
166
167 then the command
168
169 git rebase --onto topicA~5 topicA~3 topicA
170
171 would result in the removal of commits F and G:
172
173 ------------
174 E---H'---I'---J' topicA
175 ------------
176
177 This is useful if F and G were flawed in some way, or should not be
178 part of topicA. Note that the argument to --onto and the <upstream>
179 parameter can be any valid commit-ish.
180
181 In case of conflict, 'git rebase' will stop at the first problematic commit
182 and leave conflict markers in the tree. You can use 'git diff' to locate
183 the markers (<<<<<<) and make edits to resolve the conflict. For each
184 file you edit, you need to tell Git that the conflict has been resolved,
185 typically this would be done with
186
187
188 git add <filename>
189
190
191 After resolving the conflict manually and updating the index with the
192 desired resolution, you can continue the rebasing process with
193
194
195 git rebase --continue
196
197
198 Alternatively, you can undo the 'git rebase' with
199
200
201 git rebase --abort
202
203 CONFIGURATION
204 -------------
205
206 rebase.stat::
207 Whether to show a diffstat of what changed upstream since the last
208 rebase. False by default.
209
210 rebase.autoSquash::
211 If set to true enable `--autosquash` option by default.
212
213 rebase.autoStash::
214 If set to true enable `--autostash` option by default.
215
216 rebase.missingCommitsCheck::
217 If set to "warn", print warnings about removed commits in
218 interactive mode. If set to "error", print the warnings and
219 stop the rebase. If set to "ignore", no checking is
220 done. "ignore" by default.
221
222 rebase.instructionFormat::
223 Custom commit list format to use during an `--interactive` rebase.
224
225 OPTIONS
226 -------
227 --onto <newbase>::
228 Starting point at which to create the new commits. If the
229 --onto option is not specified, the starting point is
230 <upstream>. May be any valid commit, and not just an
231 existing branch name.
232 +
233 As a special case, you may use "A\...B" as a shortcut for the
234 merge base of A and B if there is exactly one merge base. You can
235 leave out at most one of A and B, in which case it defaults to HEAD.
236
237 <upstream>::
238 Upstream branch to compare against. May be any valid commit,
239 not just an existing branch name. Defaults to the configured
240 upstream for the current branch.
241
242 <branch>::
243 Working branch; defaults to HEAD.
244
245 --continue::
246 Restart the rebasing process after having resolved a merge conflict.
247
248 --abort::
249 Abort the rebase operation and reset HEAD to the original
250 branch. If <branch> was provided when the rebase operation was
251 started, then HEAD will be reset to <branch>. Otherwise HEAD
252 will be reset to where it was when the rebase operation was
253 started.
254
255 --quit::
256 Abort the rebase operation but HEAD is not reset back to the
257 original branch. The index and working tree are also left
258 unchanged as a result.
259
260 --keep-empty::
261 Keep the commits that do not change anything from its
262 parents in the result.
263
264 --skip::
265 Restart the rebasing process by skipping the current patch.
266
267 --edit-todo::
268 Edit the todo list during an interactive rebase.
269
270 -m::
271 --merge::
272 Use merging strategies to rebase. When the recursive (default) merge
273 strategy is used, this allows rebase to be aware of renames on the
274 upstream side.
275 +
276 Note that a rebase merge works by replaying each commit from the working
277 branch on top of the <upstream> branch. Because of this, when a merge
278 conflict happens, the side reported as 'ours' is the so-far rebased
279 series, starting with <upstream>, and 'theirs' is the working branch. In
280 other words, the sides are swapped.
281
282 -s <strategy>::
283 --strategy=<strategy>::
284 Use the given merge strategy.
285 If there is no `-s` option 'git merge-recursive' is used
286 instead. This implies --merge.
287 +
288 Because 'git rebase' replays each commit from the working branch
289 on top of the <upstream> branch using the given strategy, using
290 the 'ours' strategy simply discards all patches from the <branch>,
291 which makes little sense.
292
293 -X <strategy-option>::
294 --strategy-option=<strategy-option>::
295 Pass the <strategy-option> through to the merge strategy.
296 This implies `--merge` and, if no strategy has been
297 specified, `-s recursive`. Note the reversal of 'ours' and
298 'theirs' as noted above for the `-m` option.
299
300 -S[<keyid>]::
301 --gpg-sign[=<keyid>]::
302 GPG-sign commits. The `keyid` argument is optional and
303 defaults to the committer identity; if specified, it must be
304 stuck to the option without a space.
305
306 -q::
307 --quiet::
308 Be quiet. Implies --no-stat.
309
310 -v::
311 --verbose::
312 Be verbose. Implies --stat.
313
314 --stat::
315 Show a diffstat of what changed upstream since the last rebase. The
316 diffstat is also controlled by the configuration option rebase.stat.
317
318 -n::
319 --no-stat::
320 Do not show a diffstat as part of the rebase process.
321
322 --no-verify::
323 This option bypasses the pre-rebase hook. See also linkgit:githooks[5].
324
325 --verify::
326 Allows the pre-rebase hook to run, which is the default. This option can
327 be used to override --no-verify. See also linkgit:githooks[5].
328
329 -C<n>::
330 Ensure at least <n> lines of surrounding context match before
331 and after each change. When fewer lines of surrounding
332 context exist they all must match. By default no context is
333 ever ignored.
334
335 -f::
336 --force-rebase::
337 Force a rebase even if the current branch is up-to-date and
338 the command without `--force` would return without doing anything.
339 +
340 You may find this (or --no-ff with an interactive rebase) helpful after
341 reverting a topic branch merge, as this option recreates the topic branch with
342 fresh commits so it can be remerged successfully without needing to "revert
343 the reversion" (see the
344 link:howto/revert-a-faulty-merge.html[revert-a-faulty-merge How-To] for details).
345
346 --fork-point::
347 --no-fork-point::
348 Use reflog to find a better common ancestor between <upstream>
349 and <branch> when calculating which commits have been
350 introduced by <branch>.
351 +
352 When --fork-point is active, 'fork_point' will be used instead of
353 <upstream> to calculate the set of commits to rebase, where
354 'fork_point' is the result of `git merge-base --fork-point <upstream>
355 <branch>` command (see linkgit:git-merge-base[1]). If 'fork_point'
356 ends up being empty, the <upstream> will be used as a fallback.
357 +
358 If either <upstream> or --root is given on the command line, then the
359 default is `--no-fork-point`, otherwise the default is `--fork-point`.
360
361 --ignore-whitespace::
362 --whitespace=<option>::
363 These flag are passed to the 'git apply' program
364 (see linkgit:git-apply[1]) that applies the patch.
365 Incompatible with the --interactive option.
366
367 --committer-date-is-author-date::
368 --ignore-date::
369 These flags are passed to 'git am' to easily change the dates
370 of the rebased commits (see linkgit:git-am[1]).
371 Incompatible with the --interactive option.
372
373 --signoff::
374 This flag is passed to 'git am' to sign off all the rebased
375 commits (see linkgit:git-am[1]). Incompatible with the
376 --interactive option.
377
378 -i::
379 --interactive::
380 Make a list of the commits which are about to be rebased. Let the
381 user edit that list before rebasing. This mode can also be used to
382 split commits (see SPLITTING COMMITS below).
383 +
384 The commit list format can be changed by setting the configuration option
385 rebase.instructionFormat. A customized instruction format will automatically
386 have the long commit hash prepended to the format.
387
388 -p::
389 --preserve-merges::
390 Recreate merge commits instead of flattening the history by replaying
391 commits a merge commit introduces. Merge conflict resolutions or manual
392 amendments to merge commits are not preserved.
393 +
394 This uses the `--interactive` machinery internally, but combining it
395 with the `--interactive` option explicitly is generally not a good
396 idea unless you know what you are doing (see BUGS below).
397
398 -x <cmd>::
399 --exec <cmd>::
400 Append "exec <cmd>" after each line creating a commit in the
401 final history. <cmd> will be interpreted as one or more shell
402 commands.
403 +
404 You may execute several commands by either using one instance of `--exec`
405 with several commands:
406 +
407 git rebase -i --exec "cmd1 && cmd2 && ..."
408 +
409 or by giving more than one `--exec`:
410 +
411 git rebase -i --exec "cmd1" --exec "cmd2" --exec ...
412 +
413 If `--autosquash` is used, "exec" lines will not be appended for
414 the intermediate commits, and will only appear at the end of each
415 squash/fixup series.
416 +
417 This uses the `--interactive` machinery internally, but it can be run
418 without an explicit `--interactive`.
419
420 --root::
421 Rebase all commits reachable from <branch>, instead of
422 limiting them with an <upstream>. This allows you to rebase
423 the root commit(s) on a branch. When used with --onto, it
424 will skip changes already contained in <newbase> (instead of
425 <upstream>) whereas without --onto it will operate on every change.
426 When used together with both --onto and --preserve-merges,
427 'all' root commits will be rewritten to have <newbase> as parent
428 instead.
429
430 --autosquash::
431 --no-autosquash::
432 When the commit log message begins with "squash! ..." (or
433 "fixup! ..."), and there is a commit whose title begins with
434 the same ..., automatically modify the todo list of rebase -i
435 so that the commit marked for squashing comes right after the
436 commit to be modified, and change the action of the moved
437 commit from `pick` to `squash` (or `fixup`). Ignores subsequent
438 "fixup! " or "squash! " after the first, in case you referred to an
439 earlier fixup/squash with `git commit --fixup/--squash`.
440 +
441 This option is only valid when the `--interactive` option is used.
442 +
443 If the `--autosquash` option is enabled by default using the
444 configuration variable `rebase.autoSquash`, this option can be
445 used to override and disable this setting.
446
447 --autostash::
448 --no-autostash::
449 Automatically create a temporary stash entry before the operation
450 begins, and apply it after the operation ends. This means
451 that you can run rebase on a dirty worktree. However, use
452 with care: the final stash application after a successful
453 rebase might result in non-trivial conflicts.
454
455 --no-ff::
456 With --interactive, cherry-pick all rebased commits instead of
457 fast-forwarding over the unchanged ones. This ensures that the
458 entire history of the rebased branch is composed of new commits.
459 +
460 Without --interactive, this is a synonym for --force-rebase.
461 +
462 You may find this helpful after reverting a topic branch merge, as this option
463 recreates the topic branch with fresh commits so it can be remerged
464 successfully without needing to "revert the reversion" (see the
465 link:howto/revert-a-faulty-merge.html[revert-a-faulty-merge How-To] for details).
466
467 include::merge-strategies.txt[]
468
469 NOTES
470 -----
471
472 You should understand the implications of using 'git rebase' on a
473 repository that you share. See also RECOVERING FROM UPSTREAM REBASE
474 below.
475
476 When the git-rebase command is run, it will first execute a "pre-rebase"
477 hook if one exists. You can use this hook to do sanity checks and
478 reject the rebase if it isn't appropriate. Please see the template
479 pre-rebase hook script for an example.
480
481 Upon completion, <branch> will be the current branch.
482
483 INTERACTIVE MODE
484 ----------------
485
486 Rebasing interactively means that you have a chance to edit the commits
487 which are rebased. You can reorder the commits, and you can
488 remove them (weeding out bad or otherwise unwanted patches).
489
490 The interactive mode is meant for this type of workflow:
491
492 1. have a wonderful idea
493 2. hack on the code
494 3. prepare a series for submission
495 4. submit
496
497 where point 2. consists of several instances of
498
499 a) regular use
500
501 1. finish something worthy of a commit
502 2. commit
503
504 b) independent fixup
505
506 1. realize that something does not work
507 2. fix that
508 3. commit it
509
510 Sometimes the thing fixed in b.2. cannot be amended to the not-quite
511 perfect commit it fixes, because that commit is buried deeply in a
512 patch series. That is exactly what interactive rebase is for: use it
513 after plenty of "a"s and "b"s, by rearranging and editing
514 commits, and squashing multiple commits into one.
515
516 Start it with the last commit you want to retain as-is:
517
518 git rebase -i <after-this-commit>
519
520 An editor will be fired up with all the commits in your current branch
521 (ignoring merge commits), which come after the given commit. You can
522 reorder the commits in this list to your heart's content, and you can
523 remove them. The list looks more or less like this:
524
525 -------------------------------------------
526 pick deadbee The oneline of this commit
527 pick fa1afe1 The oneline of the next commit
528 ...
529 -------------------------------------------
530
531 The oneline descriptions are purely for your pleasure; 'git rebase' will
532 not look at them but at the commit names ("deadbee" and "fa1afe1" in this
533 example), so do not delete or edit the names.
534
535 By replacing the command "pick" with the command "edit", you can tell
536 'git rebase' to stop after applying that commit, so that you can edit
537 the files and/or the commit message, amend the commit, and continue
538 rebasing.
539
540 If you just want to edit the commit message for a commit, replace the
541 command "pick" with the command "reword".
542
543 To drop a commit, replace the command "pick" with "drop", or just
544 delete the matching line.
545
546 If you want to fold two or more commits into one, replace the command
547 "pick" for the second and subsequent commits with "squash" or "fixup".
548 If the commits had different authors, the folded commit will be
549 attributed to the author of the first commit. The suggested commit
550 message for the folded commit is the concatenation of the commit
551 messages of the first commit and of those with the "squash" command,
552 but omits the commit messages of commits with the "fixup" command.
553
554 'git rebase' will stop when "pick" has been replaced with "edit" or
555 when a command fails due to merge errors. When you are done editing
556 and/or resolving conflicts you can continue with `git rebase --continue`.
557
558 For example, if you want to reorder the last 5 commits, such that what
559 was HEAD~4 becomes the new HEAD. To achieve that, you would call
560 'git rebase' like this:
561
562 ----------------------
563 $ git rebase -i HEAD~5
564 ----------------------
565
566 And move the first patch to the end of the list.
567
568 You might want to preserve merges, if you have a history like this:
569
570 ------------------
571 X
572 \
573 A---M---B
574 /
575 ---o---O---P---Q
576 ------------------
577
578 Suppose you want to rebase the side branch starting at "A" to "Q". Make
579 sure that the current HEAD is "B", and call
580
581 -----------------------------
582 $ git rebase -i -p --onto Q O
583 -----------------------------
584
585 Reordering and editing commits usually creates untested intermediate
586 steps. You may want to check that your history editing did not break
587 anything by running a test, or at least recompiling at intermediate
588 points in history by using the "exec" command (shortcut "x"). You may
589 do so by creating a todo list like this one:
590
591 -------------------------------------------
592 pick deadbee Implement feature XXX
593 fixup f1a5c00 Fix to feature XXX
594 exec make
595 pick c0ffeee The oneline of the next commit
596 edit deadbab The oneline of the commit after
597 exec cd subdir; make test
598 ...
599 -------------------------------------------
600
601 The interactive rebase will stop when a command fails (i.e. exits with
602 non-0 status) to give you an opportunity to fix the problem. You can
603 continue with `git rebase --continue`.
604
605 The "exec" command launches the command in a shell (the one specified
606 in `$SHELL`, or the default shell if `$SHELL` is not set), so you can
607 use shell features (like "cd", ">", ";" ...). The command is run from
608 the root of the working tree.
609
610 ----------------------------------
611 $ git rebase -i --exec "make test"
612 ----------------------------------
613
614 This command lets you check that intermediate commits are compilable.
615 The todo list becomes like that:
616
617 --------------------
618 pick 5928aea one
619 exec make test
620 pick 04d0fda two
621 exec make test
622 pick ba46169 three
623 exec make test
624 pick f4593f9 four
625 exec make test
626 --------------------
627
628 SPLITTING COMMITS
629 -----------------
630
631 In interactive mode, you can mark commits with the action "edit". However,
632 this does not necessarily mean that 'git rebase' expects the result of this
633 edit to be exactly one commit. Indeed, you can undo the commit, or you can
634 add other commits. This can be used to split a commit into two:
635
636 - Start an interactive rebase with `git rebase -i <commit>^`, where
637 <commit> is the commit you want to split. In fact, any commit range
638 will do, as long as it contains that commit.
639
640 - Mark the commit you want to split with the action "edit".
641
642 - When it comes to editing that commit, execute `git reset HEAD^`. The
643 effect is that the HEAD is rewound by one, and the index follows suit.
644 However, the working tree stays the same.
645
646 - Now add the changes to the index that you want to have in the first
647 commit. You can use `git add` (possibly interactively) or
648 'git gui' (or both) to do that.
649
650 - Commit the now-current index with whatever commit message is appropriate
651 now.
652
653 - Repeat the last two steps until your working tree is clean.
654
655 - Continue the rebase with `git rebase --continue`.
656
657 If you are not absolutely sure that the intermediate revisions are
658 consistent (they compile, pass the testsuite, etc.) you should use
659 'git stash' to stash away the not-yet-committed changes
660 after each commit, test, and amend the commit if fixes are necessary.
661
662
663 RECOVERING FROM UPSTREAM REBASE
664 -------------------------------
665
666 Rebasing (or any other form of rewriting) a branch that others have
667 based work on is a bad idea: anyone downstream of it is forced to
668 manually fix their history. This section explains how to do the fix
669 from the downstream's point of view. The real fix, however, would be
670 to avoid rebasing the upstream in the first place.
671
672 To illustrate, suppose you are in a situation where someone develops a
673 'subsystem' branch, and you are working on a 'topic' that is dependent
674 on this 'subsystem'. You might end up with a history like the
675 following:
676
677 ------------
678 o---o---o---o---o---o---o---o master
679 \
680 o---o---o---o---o subsystem
681 \
682 *---*---* topic
683 ------------
684
685 If 'subsystem' is rebased against 'master', the following happens:
686
687 ------------
688 o---o---o---o---o---o---o---o master
689 \ \
690 o---o---o---o---o o'--o'--o'--o'--o' subsystem
691 \
692 *---*---* topic
693 ------------
694
695 If you now continue development as usual, and eventually merge 'topic'
696 to 'subsystem', the commits from 'subsystem' will remain duplicated forever:
697
698 ------------
699 o---o---o---o---o---o---o---o master
700 \ \
701 o---o---o---o---o o'--o'--o'--o'--o'--M subsystem
702 \ /
703 *---*---*-..........-*--* topic
704 ------------
705
706 Such duplicates are generally frowned upon because they clutter up
707 history, making it harder to follow. To clean things up, you need to
708 transplant the commits on 'topic' to the new 'subsystem' tip, i.e.,
709 rebase 'topic'. This becomes a ripple effect: anyone downstream from
710 'topic' is forced to rebase too, and so on!
711
712 There are two kinds of fixes, discussed in the following subsections:
713
714 Easy case: The changes are literally the same.::
715
716 This happens if the 'subsystem' rebase was a simple rebase and
717 had no conflicts.
718
719 Hard case: The changes are not the same.::
720
721 This happens if the 'subsystem' rebase had conflicts, or used
722 `--interactive` to omit, edit, squash, or fixup commits; or
723 if the upstream used one of `commit --amend`, `reset`, or
724 `filter-branch`.
725
726
727 The easy case
728 ~~~~~~~~~~~~~
729
730 Only works if the changes (patch IDs based on the diff contents) on
731 'subsystem' are literally the same before and after the rebase
732 'subsystem' did.
733
734 In that case, the fix is easy because 'git rebase' knows to skip
735 changes that are already present in the new upstream. So if you say
736 (assuming you're on 'topic')
737 ------------
738 $ git rebase subsystem
739 ------------
740 you will end up with the fixed history
741 ------------
742 o---o---o---o---o---o---o---o master
743 \
744 o'--o'--o'--o'--o' subsystem
745 \
746 *---*---* topic
747 ------------
748
749
750 The hard case
751 ~~~~~~~~~~~~~
752
753 Things get more complicated if the 'subsystem' changes do not exactly
754 correspond to the ones before the rebase.
755
756 NOTE: While an "easy case recovery" sometimes appears to be successful
757 even in the hard case, it may have unintended consequences. For
758 example, a commit that was removed via `git rebase
759 --interactive` will be **resurrected**!
760
761 The idea is to manually tell 'git rebase' "where the old 'subsystem'
762 ended and your 'topic' began", that is, what the old merge-base
763 between them was. You will have to find a way to name the last commit
764 of the old 'subsystem', for example:
765
766 * With the 'subsystem' reflog: after 'git fetch', the old tip of
767 'subsystem' is at `subsystem@{1}`. Subsequent fetches will
768 increase the number. (See linkgit:git-reflog[1].)
769
770 * Relative to the tip of 'topic': knowing that your 'topic' has three
771 commits, the old tip of 'subsystem' must be `topic~3`.
772
773 You can then transplant the old `subsystem..topic` to the new tip by
774 saying (for the reflog case, and assuming you are on 'topic' already):
775 ------------
776 $ git rebase --onto subsystem subsystem@{1}
777 ------------
778
779 The ripple effect of a "hard case" recovery is especially bad:
780 'everyone' downstream from 'topic' will now have to perform a "hard
781 case" recovery too!
782
783 BUGS
784 ----
785 The todo list presented by `--preserve-merges --interactive` does not
786 represent the topology of the revision graph. Editing commits and
787 rewording their commit messages should work fine, but attempts to
788 reorder commits tend to produce counterintuitive results.
789
790 For example, an attempt to rearrange
791 ------------
792 1 --- 2 --- 3 --- 4 --- 5
793 ------------
794 to
795 ------------
796 1 --- 2 --- 4 --- 3 --- 5
797 ------------
798 by moving the "pick 4" line will result in the following history:
799 ------------
800 3
801 /
802 1 --- 2 --- 4 --- 5
803 ------------
804
805 GIT
806 ---
807 Part of the linkgit:git[1] suite