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

[Jonathan Nieder <jrnieder@gmail.com>]

Russ Allbery wrote:

>                                                 Maybe we should just
> document them as they are and be explicit about the limitations, saying
> things like:
>
>     The information in the Vcs-* header should be sufficient to locate the
>     repository used for packaging and access it anonymously.  It may or
>     may not be the branch used for packaging any specific version of the
>     package, and the packaging is not necessarily on the default branch.
>     Additional investigation is often required to find the part of the
>     repository used for current development or for any particular version
>     of the package.
>
> If, over time, debcheckout and our package metadata starts making more
> explicit guarantees, we can always tighten the language later, but the
> above reflects the current state of the archive.

That sounds sensible to me.

Thanks,
Jonathan