/usr/lib/x86_64-linux-gnu/lua/5.2/rex_gnu.so is in lua-rex-gnu 2.7.2-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/lua/5.2/../../liblua5.2-rex-gnu.so.0.0.0
/usr/lib/x86_64-linux-gnu/lua/5.2/../../liblua5.2-rex-gnu.so.0.0.0