[3.6] bpo-24960: use pkgutil.get_data in lib2to3 to read pickled grammar files (GH-4977) by miss-islington · Pull Request #4979 · python/cpython
This is more complicated than it should be because we need to preserve the
useful mtime-based regeneration feature that lib2to3.pgen2.driver.load_grammar
has. We only look for the pickled grammar file with pkgutil.get_data and only if
the source file does not exist.
(cherry picked from commit 8a58771)