older versions of the library return this instead..

ui/medashare/magic.py

@@ -405,7 +405,8 @@ def detect_from_filename(filename):
     t = x.mimecomp_magic.file(filename)
 
     # if there's a decomp error, don't look at decomp
-    if t.startswith('application/x-decompression-error'):
+    if t.startswith('application/x-decompression-error') or \
+        t.startswith('gzip ERROR: Unknown compression format'):
         return _create_filemagic(x.mime_magic.file(filename),
                                  x.none_magic.file(filename))