The problem is in os.py. This patch fixes it:

Index: Lib/os.py
===================================================================
--- Lib/os.py   (Revision 69769)
+++ Lib/os.py   (Arbeitskopie)
@@ -372,8 +372,8 @@
                 saved_exc = e
                 saved_tb = tb
     if saved_exc:
-        raise error(saved_exc).with_traceback(saved_tb)
-    raise error(last_exc).with_traceback(tb)
+        raise saved_exc.with_traceback(saved_tb)
+    raise last_exc.with_traceback(tb)


I suspect there may be other instances of this problem (I guess 2to3
converted that).