Bug#654958: debian-policy: Document VCS fields.

[Jonathan Nieder <jrnieder@gmail.com>]

Charles Plessy wrote:

> For Git, as discussed in this thread, it is not possible to specify the branch
> in the URL.  I hope that it will be possible one day

Git URLs deliberately represent a repository, not a branch.  That is
because branches and repositories for a package are simply different
notions in git (unlike in Subversion, where they are both described by
a path relative to the root of a repository shared by multiple
packages).  This is not specific to Git but is a feature shared by
CVS, for example.

To represent a branch in a remote repository, one generally uses a Git
URL, followed by a space, followed by the branch name.  This is the
syntax accepted by "git pull":

	git pull git://git.example.com/path/to/repo for-charles

And it is the syntax generated by pull requests with the "git request-pull"
command.

All that said, I'm happy with any delimiter for the Vcs-Git field, as
long as it is not too ugly and it works.  And regarding git, I am
happy to be proven wrong if someone has ideas that lead to a better
workflow without breaking existing users too much (file a bug report
when you find them.:)).

Hope that helps,
Jonathan