3.13.0-128.177) is not available, but a newer one is (3.13.0-166.216). We redirected you there.
/usr/share/doc/python-mako/changelog is in python-mako-doc 1.0.3+ds1-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/python-mako/../python-mako-doc/rst/changelog.txt