Incorrect syntax highlighting with py-underscore-word-syntax-p

When I set py-underscore-word-syntax-p, function definitions containing the words print and/or file are incorrectly highlighted. For example:

def print_this_file():

When _ is treated as a word character, it correctly highlights with print_this_file in py-def-face. When _ isn't a word character, it incorrectly highlights with print in font-lock-keyword-face, _this_ in default, and file in py-builtins-face. Other keywords and builtins highlight correctly in all cases.

The problem seems to be the font-lock-add-keywords call to conditionally set the highlighting of print and file depending on Python version. That adds the two keywords to the front of font-lock-keywords, giving them higher priority than function definitions, etc.

According to the docs, font-lock-add-keywords accepts an optional how argument, and setting that to t adds the keywords to the end of the list instead of the beginning. That fixes the function def problem for me, but I haven't checked for any other effects it might have.

As an aside, would it be worth having py-python-edit-version default to "python3" now that Python 2 has been unsupported for a while? As far as I can tell, the only place that's referenced is the print/file keyword setup.

Thanks!