/usr/lib/python2.7/dist-packages/zope.principalannotation-3.6.1-nspkg.pth is in python-zope.principalannotation 3.6.1-0ubuntu4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/python2.7/dist-packages/../../../share/pyshared/zope.principalannotation-3.6.1-nspkg.pth