mako/_ast_util.py has the standard mako header at the top listing copyright holder as the mako authors and license terms as MIT. But the docstring that immediately follows says that the copyright holder is Armin Ronacher and license is the Python License.
These are compatible so it's not a big deal whatever permutation this turns out to be but it would be great to get clarification in the header of whether this file is actually under the Python or MIT license or both.