Objects with __slots__ set, are not updated properly

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Run the MUD framework.
2. Edit a slots based class that has instances.
3. Save the file.

What is the expected output? What do you see instead?

The expected output is that all instances are updated and continue to work.  

Instead..

Traceback (most recent call last):
  File "D:\SVN\_googlecode\sorrows-mudlib\trunk\contrib\uthread.py", line 95, in newFunction
    oldFunction(*args, **kwargs)
  File "D:\SVN\_googlecode\sorrows-mudlib\trunk\games\roguelike\services\world.py", line 340, in RunNPC
    matches = self.FindMovementDirections(body.position)
  File "D:\SVN\_googlecode\sorrows-mudlib\trunk\games\roguelike\services\world.py", line 315, in FindMovementDirections
    if self.IsTileUnoccupied(tile):
  File "D:\SVN\_googlecode\sorrows-mudlib\trunk\games\roguelike\services\world.py", line 285, in IsTileUnoccupied
    return tile.isPassable
  File "D:\SVN\_googlecode\sorrows-mudlib\trunk\games\roguelike\services\world.py", line 43, in isPassable
    return self.flags & FLAG_PASSABLE
TypeError: descriptor 'flags' for 'Tile' objects doesn't apply to 'Tile' object

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Original issue reported on code.google.com by richard.m.tew@gmail.com on 6 Sep 2010 at 10:30