Amending the message of Git commit made before a merge

Question

I committed some test code before merging in a remote branch. This merge had a lot of conflicts and took some serious time to put right. So my history looks something like this:

7ab562c Merge from remote branch ... whole load of commits brought across from the remote branch... f3e71c2 Temporary TESTING COMMIT 

The test code is fine, I really just want to change the commit message. Normally I'd go right ahead with a git rebase -i f3e71c2^ (since none of this has been pushed yet), but I've been told by a colleague that this will mess up the merge. I really don't want to mess up the merge :)

Is my colleague correct? And if so, is there anything I can do, or do I just need to live with this history?

Answer 1

You can try a git rebase --preserve-merges --interactive, with:

-p --preserve-merges 

Instead of ignoring merges, try to recreate them.

The BUG section of the man page includes:

The todo list presented by --preserve-merges --interactive does not represent the topology of the revision graph.
Editing commits and rewording their commit messages should work fine, but attempts to reorder commits tend to produce counterintuitive results.

---

As jthill's comment describes (since -p will better preserve merges if conflict resolutions were recorder):

You can retroactively light rerere for a merge:

git config rerere.enabled true git checkout $merge^1  git merge $merge^2 # for Windows:  # git merge $merge^^2  git read-tree --reset -u $merge git commit -m- git checkout @{-1} 

As noted by Soufiane Roui in the comments:

For Windows CMD users, use double caret to point for parents of the merge commit (e.g $merge^^1 instead of $merge^1).
Because the caret is considered as an escape character.