Having had a quick look into the issue it seems this stems from "compiz-gnome (<< 1:0.8.4-0ubuntu14)" in metacity 1:2.30.0-0ubuntu1, whereas compiz-gnome (and compiz) in the archive are at 1:0.8.4-0ubuntu13.
Attached are the relevant portions of apt.log.
Having had a quick look into the issue it seems this stems from "compiz-gnome (<< 1:0.8.4-0ubuntu14)" in metacity 1:2.30.0-0ubuntu1, whereas compiz-gnome (and compiz) in the archive are at 1:0.8.4-0ubuntu13.
Attached are the relevant portions of apt.log.