Now it creates /var/lib/lib/rarian because of portage setting --localstatedir to /var/lib. This should be overridden in the ebuild.
I can confirm this. The default localstatedir used by configure is /var, to which it appends a "/lib/rarian". Looks like our ebuilds should add a --localstatedir=/var to override the portage default. (this is what dbus and dbus-glib do for the same circumstances)
*** Bug 218143 has been marked as a duplicate of this bug. ***
fixed without a bump, thanks for reporting.