bug#20325: convert "fixes:debbugs:123" in log to (Bug#123) in ChangeLog

[Glenn Morris]

Paul Eggert wrote:

> Wouldn't it be better to use the same format in commit messages and in
> ChangeLog.2?  That will be less confusing for everybody.

I didn't have a problem with it (different formats), and judging from
the logs not many other people seemed to either. For a long time, Emacs
has provided the tools to seamlessly create a commit log in the right
format from a ChangeLog. I'd have preferred to see gitlog-to-changelog
get the small update needed to go in the other direction, rather than
having the Emacs convention changed (soon after we just had a brand-new
repo created using the "fixes: debbugs:123" convention throughout). (But
since it's already a fait accompli this is just me bitching rather than
asking you to change it back.)

Presumably this means the solution to http://debbugs.gnu.org/20324
will be to modify gitlog-to-changelog to recognize "(tiny change)".
Emacs will still need to be modified to pass (tiny change) through to
the VC log though.