/usr/share/pixmaps/plt-16x16.png is in racket 6.3-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/pixmaps/../racket/pkgs/icons/plt-16x16.png
/usr/share/pixmaps/../racket/pkgs/icons/plt-16x16.png