[rfc] Readonly/mirror branches

[Aaron Bentley]

John Arbash Meinel wrote:
> I've been thinking about my workspace, and I have a bunch of mirrors of
> other people's projects. And I was thinking that it would be nice to
> mark all of those mirrors as non-committable, but that I can update them
> from their parents.
> (So pull is allowed, but commit is not).

I think that bound branches should work for this.  I know that it
presently doesn't.

That means that we should fix bzr checkout to work when the source is a
readonly branch.

I'm willing to be convinced that mirrors should be something different
from bound branches, but so far, I haven't heard a convincing argument.

Aaron