Bug Correction: Avoid double execution when the application throws NameError exception.

--HG--
branch : patch1

setuptools/script template (dev).py

 # EASY-INSTALL-DEV-SCRIPT: %(spec)r,%(script_name)r
 __requires__ = """%(spec)r"""
+import sys
 from pkg_resources import require
 require("""%(spec)r""")
 del require
 __file__ = """%(dev_path)r"""
-try:
+if sys.version_info < (3, 0):
     execfile(__file__)
-except NameError:
+else:
     exec(compile(open(__file__).read(), __file__, 'exec'))