added builtin b/w compat module.
changed testing of exec.
diff --git a/Lib/builtin.py b/Lib/builtin.py
new file mode 100755
index 0000000..710d825
--- /dev/null
+++ b/Lib/builtin.py
@@ -0,0 +1,3 @@
+# B/W compat hack so code that says "import builtin" won't break after
+# name change from builtin to __builtin__.
+from __builtin__ import *