convert shebang lines: python -> python3
diff --git a/Demo/distutils/test2to3/maintest.py b/Demo/distutils/test2to3/maintest.py
index 72a26dd..036dd4f 100644
--- a/Demo/distutils/test2to3/maintest.py
+++ b/Demo/distutils/test2to3/maintest.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # The above line should get replaced with the path to the Python
 # interpreter; the block below should get 2to3-converted.