RFC: remove traceback from "newer branch format than your bzr"

[Andrew Bennetts]

Martin Pool wrote:
[...]
> I don't think it's worth worrying about the case of "still running but
> can't write to disk".  It doesn't happen often.  We often are still
> running but can't reach a remote server, but it'd be hard to get to a
> point where local IO can't work.

The most likely case I can think of is “disk full”.  In that situation I don't
think there's much we can do; filling the terminal instead of a file is
presumably not much use.  It may be worth testing that the attempt to write a
crash dump fails gracefully in that case? (rather than giving a traceback!)

-Andrew.