Index: Lib/doctest.py
===================================================================
--- Lib/doctest.py	(revision 73236)
+++ Lib/doctest.py	(working copy)
@@ -812,7 +812,7 @@
         # DocTestFinder._find_lineno to find the line number for a
         # given object's docstring.
         try:
-            file = inspect.getsourcefile(obj) or inspect.getfile(obj)
+            file = inspect.getsourcefile(obj)
             if module is not None:
                 # Supply the module globals in case the module was
                 # originally loaded via a PEP 302 loader and