diff -r fd69e2f2cb72 Lib/importlib/_bootstrap.py --- a/Lib/importlib/_bootstrap.py Mon Mar 14 18:58:41 2011 +0200 +++ b/Lib/importlib/_bootstrap.py Mon Mar 14 22:55:12 2011 +0100 @@ -304,7 +304,7 @@ def _bytes_from_bytecode(self, fullname, data, source_mtime): """Return the marshalled bytes from bytecode, verifying the magic - number and timestamp alon the way. + number and timestamp along the way. If source_mtime is None then skip the timestamp check.