For what it's worth, I backed out the integer-related face changes (trunk bzr 114993, 2013-11-06 00:14:56 UTC) and the bug was still there. This tends to confirm the guess that the bug is in the :distant-foreground-related changes (circa trunk bzr 114895, 2013-11-01 15:47:10 UTC).
- [O] bug#15815: 24.3.50; distant-foreground face attribute a... Paul Eggert