[patch] warn on deprecated formats

[Matthieu Moy]

Martin Pool <mbp at canonical.com> writes:

> Robert suggested we should put something like this in for 0.9 to remind
> people to upgrade.  I agree.

I'm not sure it's a good thing to display this warning
unconditionally. If I branch from a remote location, I usually have no
control on the remote format's branch.

OTOH, there's no reliable way to guess whether a branch is yours or
someone else's, so ...

-- 
Matthieu