bad assertions it wt4._add()?

[Martin Pool]

bwilson(?) on irc reported an assertion failure when committing a file
whose name contains '..'.  I can't actually reproduce it, but these
lines do look suspicious:

    @needs_tree_write_lock
    def _add(self, files, ids, kinds):
        """See MutableTree._add."""
        state = self.current_dirstate()
        for f, file_id, kind in zip(files, ids, kinds):
            f = f.strip('/')
            assert '//' not in f
            assert '..' not in f

At those lines, f should be a single filename? And I don't see why we
should be making those assertions about it.

-- 
Martin