/usr/lib/python2.7/dist-packages/gnuradio/blks2impl/pfb_decimator.py is in gnuradio 3.5.3.2-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/python2.7/dist-packages/gnuradio/blks2impl/../../../../../share/pyshared/gnuradio/blks2impl/pfb_decimator.py