D2897: fix: new extension for automatically modifying file contents

[hooper (Danny Hooper)]

hooper added inline comments.

INLINE COMMENTS

> pulkit wrote in test-fix.t:813
> This should respect `experimental.evolution.allowunstable` and error out if set to False.

Maybe the comment is poorly worded. I mean that an incorrect implementation could create an orphan in this case, even though both commits were meant to be replaced.

I'm adding a separate test case for aborting if the user asks to create an orphan. I imitated an abort from histedit, which seems like it should be a utility function (checknodescendants).

> pulkit wrote in test-fix.t:857
> When the working directory parent get obsoleted because of `fix`, we should update to it's successor similar to what other commands do.

Would it abort or merge if the working copy is dirty? Is that behavior expected to end up in cleanupnodes? It could also just force --working-dir. It's similar to creating an orphan if we don't fix the dirty working copy.

One of my goals is to avoid any need for merging or conflict resolution in this command.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D2897

To: hooper, #hg-reviewers
Cc: durin42, krbullock, martinvonz, yuja, indygreg, pulkit, mercurial-devel