/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/040-copy-package-cache is in ltsp-server 5.4.2-6+deb7u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/../Debian/040-copy-package-cache