This is Bugs Everywhere (BE), a bugtracker built on distributed
version control.  It works with Arch, Bazaar, Darcs, Git, Mercurial,
and Monotone at the moment, but is easily extensible.  It can also
function with no VCS at all.

The idea is to package the bug information with the source code,
so that bugs can be marked "fixed" in the branches that fix them.
So, instead of numbers, bugs have globally unique ids.