[MERGE] fetch refactoring resend

[Andrew Bennetts]

bb:tweak

Looks good to me, just one nit:

Robert Collins wrote:
> === modified file 'bzrlib/remote.py'
[...]
> +    @property
> +    def _serializer(self):
> +        # We should only be getting asked for the serializer for
> +        # RemoteRepositoryFormat objects except when the RemoteRepositoryFormat
> +        # object is a concrete instance for a RemoteRepository. In this case
> +        # we know the creating_repo and can use it to supply the serializer.
> +        self._creating_repo._ensure_real()
> +        return self._creating_repo._real_repository._format._serializer

The comment doesn't quite parse for me.  I think it should read “We should not
be getting asked ...”?

-Andrew.