/usr/lib/x86_64-linux-gnu/libboost_python.a is in libboost-python1.58-dev 1.58.0+dfsg-5ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libboost_python-py27.a
/usr/lib/x86_64-linux-gnu/libboost_python-py27.a