We should figure out if we really need to be putting things in / or not. I assume because of the nature of the package, we do, but I haven't verified that. We weren't until recently even handling that split correctly, although right now we do it unconditionally as a bandaid for bug 883759.
commit b0874f66ad6380825b69309eb6deb5c69c345912 Author: Mike Gilbert <floppym@gentoo.org> Date: Thu Mar 23 11:38:06 2023 -0400 sys-fs/multipath-tools: pass usr_prefix to make Signed-off-by: Mike Gilbert <floppym@gentoo.org> helps this a bit, I think? not sure if there's anything left here, especially given split-usr-without-initramfs is no longer supported
I think that commit was mostly about EPREFIX. The Makefile has defaults usr_prefix=${prefix} if prefix is not empty, so we need to pass usr_prefix=${EPREFIX}/usr to override that. In any case, the Makefile seems to be wired up to install most of its bins and libs in / by default.
