D821: unamend: move fb extension unamend to core

[pulkit (Pulkit Goyal)]

pulkit added inline comments.

INLINE COMMENTS

> durin42 wrote in uncommit.py:265
> Should we also look for unamend_source in the extra, and potentially refuse to unamend an unamend? Or not?

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.

REPOSITORY
  rHG Mercurial

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

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