Reducing allowed Vcs for packaging?

[Bastian Germann <bage@debian.org>]

Hi!

During the last weeks I had a look at the Vcs situation in Debian. Currently,
there are eight possible systems allowed and one might specify several of them for
one package. No package makes use of several Vcs references and frankly I do not
see why this was supported in the first place.

For the allowed systems the situation in unstable is the following:
arch is used by 2 packages pointing to bad URLs: #1025510, 1025511.
bzr is used by ~50 packages, half of which point to bad URLs.
cvs is used by 3 packages, 2 of which point to bad URLs: #1031312, #1031313.
svn is used by ~130 packages, many of which point to bad URLs.
darcs, mtn, and hg are not used.

We can see: The Vcs wars are over; with git there is a clear winner and in my
opinion, we should remove the possibility to use most of them for package
maintenance. It is one additional barrier to get into package maintenance and
we should remove the barriers that are not necessary.

I would like to suggest removing the possibility to specify several systems and
removing all systems except bzr, svn, and git, while deprecating bzr and possibly svn.
This means solving the four listed bugs and convincing the cvsd maintainer to
switch or drop the Vcs-Cvs reference. Then, the Debian Developer's Reference
should specify the changes in §6.2.5 and whatever parses Vcs-* in debian/control
should be adapted to do the specified thing.

Finally, we can drop the orphaned packages {cvs,mercurial}-buildpackage
(see #1026433) and add deprecation notices in brz-debian and svn-buildpackage.

Thanks for any comments,
Bastian