/usr/lib/python2.6/dist-packages/gbp/scripts/buildpackage.py is in git-buildpackage 0.6.0~git20120601.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/python2.6/dist-packages/gbp/scripts/../../../../../share/pyshared/gbp/scripts/buildpackage.py