Bug#1016203: vcswatch: check debian/latest branch as well (DEP-14)

[Gioele Barabucci <gioele@svario.it>]

Package: qa.debian.org

Dear vcswatch maintainers,

could you please add support for repositories that use `debian/latest` 
as the branch for their packaging work?

DEP-14 states:

> In Debian this means that uploads to unstable and experimental should
> be prepared either in the `debian/latest` branch or [...]

However currently vcswatch reports an error if a repository uses that 
branch:

> Error: debian/changelog not found in any branch (tried master, 
debian, debian/master, debian/sid, master)

Adding `debian/latest` to this list of tested branches would fix the 
problem.

Regards,

--
Gioele Barabucci