Oops, Sjoerd was in a hurry. This patch from him fixes some length

math in the Chunk class.

Lib/chunk.py

@@ -61,6 +61,7 @@ class Chunk:
             self.chunksize = struct.unpack('>l', file.read(4))[0]
         except struct.error:
             raise EOFError
+        self.chunksize = self.chunksize - 8 # subtract header
         self.size_read = 0
         self.offset = self.file.tell()