Whoops. I see what has happened. I built a new version of gnome-commander, moved the older one to extra, but didn't move the library at the same time.
I'll not have time to move it for a few days. So, you can enable the testing repo, upgrade gnome-commander to the most recent build, then disable testing. Or wait a few day until I have time to move the relevant library to extra as well.
Sorry about that....