When shutting down, openrc announces "unmounting loopback devices". The devices being unmounted are actually called "loop devices" (see man losetup). "loopback" is probably a mix-up with networking. Patch in a second.
Created attachment 262403 [details, diff] loopback device -> loop device
Fixed on overlay. http://git.overlays.gentoo.org/gitweb/?p=proj/openrc.git;a=commit;h=c8b5078660f2b94b3c64f0a71ea6cde7df76678e
we dont usually refer to the main proj repo as "overlay" as it can be confused with the normal use of the word "overlay". also, your changelog needs improving. please provide useful descriptions in the future as well as link things. see any of the commits made by me as an example.