Commit a forgotten chunk of 4d0f773d5e21. This is the change to the file tests/automated/test-harness.el. See the tests/ChangeLog of that commit, http://mid.gmane.org/E1J1MtP-0000bo-Vw@alioth.debian.org for the details.

# Force the window background to be the same as the default face background:
# white.

style "default_background"
{
	bg[NORMAL] = { 1.0, 1.0, 1.0 }
}

class "GtkXEmacs" style "default_background"