I solved this problem by improving the DPD regexes for server-to-server
IRC (it's in fastpath). I'll put a note in Gregor's ticket to refer back
to this ticket for information about the DPD inadequacies related to IRC.
Note that we should still fix the IRC analyzer. The signatures should just be a hint for the analyzer (to speed things up) and that the analyzer can detect whether it's parsing the right protocol. Without resource constraint, DPD could/would run all analyzers on all connections and then analyzers and if an analyzer can't parse the connection it detaches from the tree.
(Not changing ticket status yet, since YMMV)