Preserve merges when rebasing

[stigkj]

Would be nice if git-up preserved merges when rebasing. It seems that can be done by setting a git config variable, though. The only problem left then is setting ORIG_HEAD to the correct value.

[aanand]

Never heard of ORIG_HEAD before - now that I've done a bit of Googling, I'm not sure I follow. ORIG_HEAD is set by pull and merge before they do their thing, according to this Stack Overflow answer.

Are you saying git-up should behave similarly and set ORIG_HEAD before it does anything, and if so, what does that have to do with preserving merges?

[stigkj]

Sorry for not explaining properly. But first: one uses ORIG_HEAD after git pull/merge to see which changes have been fetched from the server in the git pull/merge, for example like this:

git log ORIG_HEAD..

As it is, git-up already behaves properly with regards to ORIG_HEAD.

Now to the issue at hand. When doing a regular rebase, any unpushed merge commits will be "flattened out". The rebase command has a --preserve-merges option which preserve merge commits when rebasing. The problem with this option is that it sets ORIG_HEAD incorrectly (look at the "Downsides to git rebase -p" section).

So if you could add an option to git-up that preserves merges it would be great! An greater still if you could point ORIG_HEAD to the correct commit afterwards.

[aanand]

OK. So merges can currently be preserved by setting git-up.rebase.arguments to --preserve-merges. Perhaps we should always set ORIG_HEAD to whatever HEAD was at the time git-up was run. Does that sound sensible, and would you be happy to implement it?

[aanand]

Closing due to quiet - if someone wants to implement and PR this, be my guest.