view CONTRIBUTING @ 44347:9c9cfecd4600

rebase: don't use rebased node as dirstate p2 (BC)

When rebasing a node, we currently use the rebased node as p2 in the
dirstate until just before we commit it (we then change to the desired
parents). This p2 is visible to the user when the rebase gets
interrupted because of merge conflicts. That can be useful to the user
as a reminder of which commit is currently being rebased, but I
believe it's incorrect for a few reasons:

 * I think the dirstate parents should be the ones that will be set
   when the commit is created.

 * I think having two parents means that you're merging those two
   commits, but when rebasing, you're generally grafting, not merging.

 * When rebasing a merge commit, we should use the two desired parents
   as dirstate parents (and we clearly can't have the rebased node as
   a third dirstate parent).

 * `hg graft` (and `hg update --merge`) sets only one parent and `hg
   rebase` should be consistent with that.

I realize that this is a somewhat large user-visible change, but I
think it's worth it because it will simplify things quite a bit.

Differential Revision: https://phab.mercurial-scm.org/D7827

Our full contribution guidelines are in our wiki, please see:

https://www.mercurial-scm.org/wiki/ContributingChanges

If you just want a checklist to follow, you can go straight to

https://www.mercurial-scm.org/wiki/ContributingChanges#Submission_checklist

If you can't run the entire testsuite for some reason (it can be
difficult on Windows), please at least run `contrib/check-code.py` on
any files you've modified and run `python contrib/check-commit` on any
commits you've made (for example, `python contrib/check-commit
273ce12ad8f1` will report some style violations on a very old commit).