D821: unamend: move fb extension unamend to core

[durham (Durham Goode)]

durham added inline comments.

INLINE COMMENTS

> pulkit wrote in uncommit.py:265
> Okay while trying to add this condition, I found we cannot refuse to unamend a changeset on the basis of unamend_source, for e.g
> `a -amend-> b -unamend-> a' -amend-> c -unamend-> a''`
> 
> But if we refuse on basis on unamend_source, unamend `c` will refuse. We need to be more smart here but when I think the other way around, I think it's okay to unamend an unamend. I am open to suggestion and will go with what you guys prefer is good.

I'd just let unamend undo an unamend.  Letting unamend toggle back and forth between the two states seems like it might grant the user more confidence in the command, even.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D821

To: pulkit, #hg-reviewers, durham
Cc: quark, durin42, ryanmce, singhsrb, durham, mercurial-devel