/usr/share/omf/xchat-gnome/xchat-gnome-sl.omf is in xchat-gnome-common 1:0.30.0~git20131003.d20b8d+really20110821-0.2ubuntu12.2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/omf/xchat-gnome/../../omf-langpack/xchat-gnome/xchat-gnome-sl.omf