Comment 36 for bug 680529

@John Meinel:

As I can see we're triggering this code path in bzrlib/config.py: TreeConfig:

    def set_option(self, value, name, section=None):
        """Set a per-branch configuration option"""
        # FIXME: We shouldn't need to lock explicitly here but rather rely on
        # higher levels providing the right lock -- vila 20101004
        self.branch.lock_write()
        try:
            self._config.set_option(value, name, section)
        finally:
            self.branch.unlock()

As you can see the branch is excplicitly locked by bzrlib itself. So, why did you blame qbzr for not taking the lock?