/usr/lib/python2.7/dist-packages/nose/tools.py is in python-nose 1.1.2-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/python2.7/dist-packages/nose/../../../../share/pyshared/nose/tools.py
/usr/lib/python2.7/dist-packages/nose/../../../../share/pyshared/nose/tools.py