The failing point is exim4.orig provides exim4, in the deptree, exim4 is essentially overridden by exim4.orig. But runlevel refers the file "exim4". Such inconsistency is the cause.
In Gentoo, a package rarely provides something. So the bug is not so severe there. Example: # rc-status Runlevel: default sshd [ started ] tincd [ started ] local [ started ] Dynamic Runlevel: hotplugged Dynamic Runlevel: needed Dynamic Runlevel: manual cp /tmp/local.orig /etc/init.d; head -11 /etc/init.d/local.orig > #!/sbin/openrc-run > # Copyright (c) 2007-2008 Roy Marples <r...@marples.name> > # Released under the 2-clause BSD license. > description="Executes user programs in /etc/local.d" > depend() > { > after * > keyword -timeout > provide local ~~~~~~~~~~~~~ provide is crucial here. # rc-status * Caching service dependencies ... [ ok ] Runlevel: default sshd [ started ] tincd [ started ] Dynamic Runlevel: hotplugged Dynamic Runlevel: needed Dynamic Runlevel: manual