D816: histedit: add copy histedit action

[durin42 (Augie Fackler)]

durin42 added inline comments.

INLINE COMMENTS

> histedit.py:864
> +    def _verifynodeconstraints(self, prev, expected, seen, basenodes):
> +        pass
> +

Shouldnt't we only allow copying things from outside the histedit stack?

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D816

To: mbthomas, #hg-reviewers, ryanmce
Cc: durin42, ryanmce, mercurial-devel