zipfile.ZipFile("bla.apk") crashes, but should not since other tools work perfectly with this file.

Python 2.7.2+ (default, Oct  4 2011, 20:06:09) 
[GCC 4.6.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import zipfile
>>> zipfile.ZipFile("bla.apk")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/zipfile.py", line 710, in __init__
    self._GetContents()
  File "/usr/lib/python2.7/zipfile.py", line 744, in _GetContents
    self._RealGetContents()
  File "/usr/lib/python2.7/zipfile.py", line 803, in _RealGetContents
    x._decodeExtra()
  File "/usr/lib/python2.7/zipfile.py", line 369, in _decodeExtra
    tp, ln = unpack('<HH', extra[:4])
struct.error: unpack requires a string argument of length 4