bug#34944: 27.0.50; FR: support amend in vc-hg

[Philipp Stephani]

Am Mi., 3. Apr. 2019 um 02:33 Uhr schrieb Dmitry Gutov <dgutov@yandex.ru>:
>
> On 22.03.2019 12:44, Philipp Stephani wrote:
> >
> > The Git integration for vc.el supports amending commits via a magic
> > changelog header.  Mercurial has the same functionality, see
> > https://www.mercurial-scm.org/wiki/EditingHistory#Amending_the_latest_changeset_with_commit_--amend.
> > If would be great to support this in Emacs as well.  Maybe the Git
> > approach could even move into main VC, and made available to all
> > backends that support amending?
>
> Here's a patch you can try (attached).
>
> No backend API change necessary, so far.
>
> Are there many backends that could support amending?

I'm not aware of others. I think for now it's fine to support
Mercurial without an API change. Once there are more backends showing
up that should have similar support, we can generalize the approach.
Thanks!