Game.__init__ tries to assign nonexistent city to player 2

[rcriii42]

Happens only occasionally

pygame 1.9.4
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Traceback (most recent call last):
  File "src/main.py", line 30, in <module>
    W = Controller.World(size)
  File "/home/rcriii/workspace/mPyre/src/Controller.py", line 31, in __init__
    self.G = Game.Game(size)
  File "/home/rcriii/workspace/mPyre/src/Game.py", line 82, in __init__
    self.players[2].assign_city(c2)
  File "/home/rcriii/workspace/mPyre/src/Player.py", line 41, in assign_city
    u.plane.destroy()
AttributeError: 'NoneType' object has no attribute 'destroy'