adding globals() to exec call for python3 compatibility

python/setup.py

@@ -52,7 +52,7 @@ def GetVersion():
 
   """
   with open(os.path.join('google', 'protobuf', '__init__.py')) as version_file:
-    exec(version_file.read())
+    exec(version_file.read(),globals())
     return __version__