Why is rebase with only rewording commit messages hitting problems?

Question

I have a branch with ~50 commits pushed to origin. Then one day, I'd like to edit the text of the commit messages (because we are using a reference to Jira task in the commit message, and I need to fix it). So the only way I know is to run an interactive rebase:

git rebase -i origin/my-precious-branch~30 my-precious-branch

and then I select a few commits and change pick to r (for reword). And what happens next is what puzzles me. For most of the commits - it simply opens the editor where I can manually alter the commit text (fine). But then it stops for one of them:

error: could not apply 616b308fe9e... OLD-MESSAGE: 1

When you have resolved this problem, run "git rebase --continue".
If you prefer to skip this patch, run "git rebase --skip" instead.
To check out the original branch and stop rebasing, run "git rebase --abort".
Could not apply 616b308fe9e3d4cd8845d090720f1cdad97add73... OLD-MESSAGE: 1

What is happening here? And why?

Describe the textual changes you made for a few commits before this happened as well as what change you made immediately before it happened. — Tim Biegeleisen, Mar 16 '18 at 08:15
The only thing I am editing in these commits is their messages. — Grzegorz Oledzki, Mar 16 '18 at 08:18
Oh. Sorry. I my changing the first line in the commits from: `OLD-MESSAGE: 1` to `NEW-MESSAGE: 2`. This was the case for the last few commits edited, incl. the very last before the error message. — Grzegorz Oledzki, Mar 16 '18 at 08:21
What does `git status` show you at the point where the rebase pauses? — Tim Biegeleisen, Mar 16 '18 at 08:24
`Unmerged paths` section says: `both modified: here/a/path/to/file/i/have/been/editing/heavily/in/the/branch.txt` — Grzegorz Oledzki, Mar 16 '18 at 08:26
You can't just rebase a merge commit like this, because you have to redo the merge, or tell Git which parent you want to follow. In general, interactive rebase is probably best avoided if merge commits are in the range of interest. — Tim Biegeleisen, Mar 16 '18 at 08:42
@TimBiegeleisen This is the answer. You should post it as such. — kowsky, Mar 16 '18 at 10:22

Tim Biegeleisen · Answer 1 · 2018-03-16T10:27:33.247

1

Based on your comments, it looks like you have one or more merge commits which your rebase is hitting. Rebasing a merge commit gets complicated, because you either have to redo the merge, or possibly let Git try to recreate the merge. In any case, the conflict you are encountering is likely due to that it is a merge commit.

See here for how to handle this situation:

Rebasing a Git merge commit

If you are prepared for such conflicts, then you may still reword the commit comments.

edited Mar 16 '18 at 10:27

answered Mar 16 '18 at 08:31

Tim Biegeleisen

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Well. It wouldn't let me just `git rebase --continue`. What I actually had was what looked like a merge conflict. So I am just manually editing the merge conflict, `git add` the file and then `git rebase --continue`. I confirm - before that I have NOT edited the contents of any "rebased" file. – Grzegorz Oledzki Mar 16 '18 at 08:33
@GrzegorzOledzki Are any of these commits _merge_ commits? – Tim Biegeleisen Mar 16 '18 at 08:35

Why is rebase with only rewording commit messages hitting problems?

1 Answers1