The encoding of sys.stderr can exist and be None.

main.py

@@ -45,7 +45,7 @@ def ReportError(script, e):
     # When the encoding of stderr is unknown (e.g. when redirected to a file),
     # output will be encoded in UTF-8; otherwise the terminal's encoding will
     # be used.
-    enc = getattr(sys.stderr, 'encoding', 'utf8')
+    enc = getattr(sys.stderr, 'encoding', 'utf8') or 'utf8'
 
     # Synchronize the UTF-8 encoded line with the output line in the
     # terminal's encoding. We need to compensate for the fact that the