--- /usr/lib/python2.7/zipfile.py	2016-07-02 21:02:36.000000000 +0200
+++ zf.py	2016-10-21 00:02:26.864716094 +0200
@@ -247,7 +247,10 @@
             return None
         endrec = list(struct.unpack(structEndArchive, recData))
         commentSize = endrec[_ECD_COMMENT_SIZE] #as claimed by the zip file
-        comment = data[start+sizeEndCentDir:start+sizeEndCentDir+commentSize]
+        comment = data[start+sizeEndCentDir:]
+        if len(comment) != commentSize:
+            # likely not a zip file, but a file that just contains the magic
+            return None
         endrec.append(comment)
         endrec.append(maxCommentStart + start)