https://bugs.freedesktop.org/show_bug.cgi?id=33762
--- Comment #4 from s3734770@mail.zih.tu-dresden.de 2011-01-31 09:41:12 PST --- i found a demo that reproduces the bug for me:
http://cgit.freedesktop.org/mesa/demos/ in /demos/shadowtex
in all programs the texture looks the same. i attached a pic how the demo looks like. watch the shadow