Sep 13th I stabilized net-analyzer/munin-2.0.5-r1 (security bug #412881). I use automated repoman checks and USE="-ipv6", and everything was fine at the time I committed the stabilization (also, see no mention of net-server in that security bug).
Sep 14th Seraphim Mellos filed bug #434978 about munin pulling in ~arch net-server.
Sep 16th x86@ team has been re-added to security bug #412881. Meanwhile Mr_Bones_ pinged me on irc. Also, Diego Elio Pettenò (flameeyes) filed bug #435242 against repoman not catching the dependency problem.
Sep 17th I stabilized dev-perl/net-server-2.6.0 on x86, fixing the immediate problem.
Sep 18th the repoman fix has been released in portage-188.8.131.52 and 2.2.0_alpha129.
Now the only remaining thing to do is pushing the portage/repoman fix to stable. I especially like how quickly the fix for root cause (repoman check) has been produced and released.