/usr/share/doc/python-werkzeug-doc/html/_static/underscore.js is in python-werkzeug-doc 0.10.4+dfsg1-1ubuntu1.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/python-werkzeug-doc/html/_static/../../../../javascript/sphinxdoc/1.0/underscore.js