I’m not too happy the devicekit-power package has become unsupported but still remains in the tree as stable, with not even a word in elog or similar. This package depends on libusb:0, which has some pretty unfortunate bugs, resulting, at least for me, in power management only half working. I praise the developers of GNOME yet again for solid code writing that chugs along and still recognizes my battery and other things despite crashes like this.
It’s pretty easy to update and move on. Simply run
emerge -1v upower and portage will handle the transition.