/usr/lib/python3.7/lib2to3/fixes/fix_execfile.py is in python3-lib2to3 3.6.5-3.
This file is owned by root:root, with mode 0o644.
It is a symlink to /usr/lib/python3.7/lib2to3/fixes/./usr/lib/python3.6/lib2to3/fixes/fix_execfile.py