py3 compatibility fixes

src/Mod/Path/PathScripts/post/opensbp_post.py

@@ -80,7 +80,7 @@ POST_OPERATION = ''''''
 TOOL_CHANGE = ''''''
 
 # to distinguish python built-in open function from the one declared below
-if open.__module__ == '__builtin__':
+if open.__module__ in ['__builtin__','io']:
     pythonopen = open
 
 CurrentState = {}