/usr/lib/python2.7/dist-packages/zope.keyreference-3.6.4-nspkg.pth is in python-zope.keyreference 3.6.4-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/python2.7/dist-packages/../../../share/pyshared/zope.keyreference-3.6.4-nspkg.pth