bug#18954: 24.4; vc-log Summary: header is included in the log message

[Dmitry Gutov <dgutov@yandex.ru>]

Ivan Shmakov <ivan@siamics.net> writes:

> 	A quick scan through vc/*.el suggest that the Summary: header is
> 	only recognized by vc-arch.el (which, however, doesn’t seem to
> 	take care of Author:), while only vc-git.el seems to recognize
> 	Author: (and doesn’t seem to care about Summary: in turn.)

Too quick a scan. log-edit-extract-headers recognizes the Summary header
by default, so the difference must be betwen backends that pipe their
commit message through that function, and those that don't.

> 	If so, this bug actually affects most of the VCS supported by
> 	the Emacs VC facility, and not just Subversion.

Quite a few of those, yes: RCS, SRC, SCCS and CVS must have this
problem, as well as the obsolete MCVS and Arch.

I'm puzzled, however, why hasn't anyone else reported this problem by
now? Maybe nobody uses most of those, but what about CVS? Do its users
just stay on older Emacs versions?

> 	• Amend the log-edit-insert-message-template function to only
> 	  generate the template if /either/ explicitly requested by the
> 	  user (as in: via a yes-maybe-no variable setting, or by
> 	  running it interactively) /or/ when the headers in question
> 	  are known to be recognized by the target VCS.

The easiest solution seems to be to teach all VC backends to recognize
it. It would be rather hard for me to test the results, though.