Don't add 'rebased-with-history from <commit>' if IMERGE_MODIFY_COMMI…

[brucehoult]

After running rebase-with-history (which is otherwise great) many times, the commit messages get horrible.

I think it's better to not modify the messages. Enable this to be opted-out of globally by setting an environment variable.

You can see the hashes of all the parents of the commit in the git log for it anyway.

[brucehoult]

No point to cache/optimise this as the subsequent git operation is far more heavyweight.

[mhagger]

I like the idea, but why an environment variable? Wouldn't it be more natural to use a git configuration setting, as we already do for imerge.editMergeMessages? That would also allow users to configure it globally or per repo.

Another question: would it be useful to add the rebased with history from <commit> line, but at the same time delete any previous such comments in the log message? That would give readers the information that rebase-with-history was involved and give them a pointer to the previous version of the commit, but not allow the messages to accumulate forever.

[brucehoult]

Ok sure git config would work.

Replacing any previous "rebased with history" (etc) line would be a better option than the current default, but I still personally prefer nothing at all.