/usr/lib/python2.7/dist-packages/google/protobuf/internal/cpp_message.py is in python-protobuf 2.4.1-1ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/python2.7/dist-packages/google/protobuf/internal/../../../../../../share/pyshared/google/protobuf/internal/cpp_message.py