/usr/lib/python2.7/dist-packages/notebook/templates/ is in python-notebook 5.2.2-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/python2.7/dist-packages/notebook/templates/404.html
/usr/lib/python2.7/dist-packages/notebook/templates/edit.html
/usr/lib/python2.7/dist-packages/notebook/templates/error.html
/usr/lib/python2.7/dist-packages/notebook/templates/login.html
/usr/lib/python2.7/dist-packages/notebook/templates/logout.html
/usr/lib/python2.7/dist-packages/notebook/templates/notebook.html
/usr/lib/python2.7/dist-packages/notebook/templates/page.html
/usr/lib/python2.7/dist-packages/notebook/templates/terminal.html
/usr/lib/python2.7/dist-packages/notebook/templates/tree.html
/usr/lib/python2.7/dist-packages/notebook/templates/view.html