[RFC] Port git gcc-descr to Python

[Jakub Jelinek]

On Thu, Oct 14, 2021 at 11:06:55AM +0200, Tobias Burnus wrote:
> Additionally, I observe the following (independent of the conversion):
> For 7433458d871f6bfe2169b9d7d04fec64bb142924, I get:
>    r0-80854-g7433458d871f6b
> The question is whether we are happy that only reversions since
> basepoints/gcc-5 have a version number or whether we want to
> use releases/gcc-x.y.0 -> x.y as fallback when basepoint does not
> exist or back-added more basepoints? Admittedly, this will add '.',
> thus, maybe the answer is 'no'?

Yes, everything older than basepoints/gcc-5 is r0-NNNNN-gNNNNNN
by design.  Digits aren't allowed there and while we could use say
underscore, it doesn't seem to be worth it for such old history,
and all the bugzilla highlighting, web redirection etc. handles just
r number - number - g hexnumber
or
r number - number
formats.  It is more common to refer to the old commits through svn
revisions anyway.

	Jakub