As for 18.01.2013, file 99-systemd.rules not installed.
What ebuild is systemd/git?
Fixed by mgorny on 19 Jan 2013.
As of 2013-01-19 00:30 UTC, the bug was fixed. In the meantime, the ebuild was package.masked. Therefore, I'd suggest you to clean up your mask file. *** This bug has been marked as a duplicate of bug 452858 ***