UnicodeEncodeError on mv of a deleted non-ascii file

[Martin Packman]

Trying to `bzr mv` a versioned file that has been deleted or renamed outside of bzr throws a UnicodeEncodeError, for instance with the commands:

    bzr init
    bzr mkdir £
    rmdir £
    bzr mv £ d

This results in the following traceback:

    Traceback (most recent call last):
      File ".../bzrlib/commands.py", line 923, in exception_to_return_code
        return the_callable(*args, **kwargs)
      File ".../bzrlib/commands.py", line 1128, in run_bzr
        ret = run(*run_argv)
      File ".../bzrlib/commands.py", line 676, in run_argv_aliases
        return self.run(**all_cmd_args)
      File ".../bzrlib/commands.py", line 698, in run
        return self._operation.run_simple(*args, **kwargs)
      File ".../bzrlib/cleanup.py", line 135, in run_simple
        self.cleanups, self.func, *args, **kwargs)
      File ".../bzrlib/cleanup.py", line 165, in _do_with_cleanups
        result = func(*args, **kwargs)
      File ".../bzrlib/builtins.py", line 891, in run
        self._run(tree, names_list, rel_names, after)
      File ".../bzrlib/builtins.py", line 981, in _run
        tree.rename_one(src, dest, after=after)
      File ".../bzrlib/mutabletree.py", line 51, in tree_write_locked
        return unbound(self, *args, **kwargs)
      File ".../bzrlib/workingtree_4.py", line 1299, in rename_one
        super(DirStateWorkingTree, self).rename_one(from_rel, to_rel, after)
      File ".../bzrlib/mutabletree.py", line 51, in tree_write_locked
        return unbound(self, *args, **kwargs)
      File ".../bzrlib/workingtree.py", line 2659, in rename_one
        rename_entries = self._determine_mv_mode(rename_entries, after)
      File ".../bzrlib/workingtree.py", line 2751, in _determine_mv_mode
        errors.PathsDoNotExist(paths=(str(from_rel),
    UnicodeEncodeError: 'ascii' codec can't encode character u'\xa3' in position 0: ordinal not in range(128)

As always, calling str() on a path is bogus.