Comment 5 for bug 1156583

Same error with frets on fire:
$ fretsonfire
Traceback (most recent call last):
  File "./FretsOnFire.py", line 45, in <module>
    from GameEngine import GameEngine
  File "/usr/share/games/fretsonfire/game/GameEngine.py", line 34, in <module>
    from Data import Data
  File "/usr/share/games/fretsonfire/game/Data.py", line 23, in <module>
    from Font import Font
  File "/usr/share/games/fretsonfire/game/Font.py", line 27, in <module>
    from Texture import Texture
  File "/usr/share/games/fretsonfire/game/Texture.py", line 30, in <module>
    import PngImagePlugin
ImportError: No module named PngImagePlugin