/usr/lib/python2.6/dist-packages/xpra/test_DoS_client.py is in xpra 0.3.11+dfsg-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/python2.6/dist-packages/xpra/../../../../share/pyshared/xpra/test_DoS_client.py