Perhaps this must be wrapped under a programmer-expected custom 
exception class (TarError maybe)

    for tarinfo in tarfileobj.getmembers():
  File "/home/apy/ActivePython-2.6/lib/python2.6/tarfile.py", line 
1791, in getmembers
    self._load()        # all members, we first have to
  File "/home/apy/ActivePython-2.6/lib/python2.6/tarfile.py", line 
2352, in _load
    tarinfo = self.next()
  File "/home/apy/ActivePython-2.6/lib/python2.6/tarfile.py", line 
2307, in next
    self.fileobj.seek(self.offset)
  File "/home/apy/ActivePython-2.6/lib/python2.6/gzip.py", line 382, in 
seek
    self.read(1024)
  File "/home/apy/ActivePython-2.6/lib/python2.6/gzip.py", line 219, in 
read
    self._read(readsize)
  File "/home/apy/ActivePython-2.6/lib/python2.6/gzip.py", line 267, in 
_read
    self._read_eof()
  File "/home/apy/ActivePython-2.6/lib/python2.6/gzip.py", line 300, in 
_read_eof
    crc32 = read32(self.fileobj)
  File "/home/apy/ActivePython-2.6/lib/python2.6/gzip.py", line 24, in 
read32
    return struct.unpack("<I", input.read(4))[0]
error: unpack requires a string argument of length 4