/usr/lib/python2.7/dist-packages/bson/son.py is in python-bson 2.1-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/python2.7/dist-packages/bson/../../../../share/pyshared/bson/son.py
/usr/lib/python2.7/dist-packages/bson/../../../../share/pyshared/bson/son.py