/usr/lib/python2.7/dist-packages/pymongo/son_manipulator.py is in python-pymongo 2.2-4+deb7u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/python2.7/dist-packages/pymongo/../../../../share/pyshared/pymongo/son_manipulator.py