Comment 2 for bug 885053

The problem:
update-alternatives: using /usr/lib/mesa/ld.so.conf to provide /etc/ld.so.conf.d/GL.conf (gl_conf) in auto mode.

dpkg-divert: mismatch on package

  when removing `diversion of /usr/lib/libGL.so.1.2 to /usr/lib/fglrx/libGL.so.1.2.xlibmesa by fglrx'

  found `diversion of /usr/lib/libGL.so.1.2 to /usr/lib/fglrx/libGL.so.1.2.xlibmesa by xorg-driver-fglrx'

dpkg: error processing fglrx (--remove):

 subprocess installed post-removal script returned error exit status 2

The solution:
sudo dpkg-divert --remove /usr/lib/libGL.so.1.2