New user state updates sometimes aren't processed correctly

[progval]

from irctest CI:

1740592607.789 1: connects to server.
1740592607.789 2: connects to server.
1740592607.789 2 -> S: NICK sender
1740592607.789 2 -> S: USER username * * :Realname
1740592607.797 S -> 2: :My.Little.Server NOTICE * :*** Looking up your hostname
1740592607.798 S -> 2: :My.Little.Server NOTICE * :*** Found your hostname: localhost
1740592607.798 S -> 2: :My.Little.Server 001 sender :Welcome to the test Internet Relay Chat network, sender
1740592607.798 S -> 2: :My.Little.Server 002 sender :Your host is My.Little.Server, running version sable-0.1.0-15f35c80a72c71a4796c5a2e04055817d989c3cb
1740592607.798 S -> 2: :My.Little.Server 003 sender :This server was created 2025-02-26 17:56:47.797522657 UTC
1740592607.798 S -> 2: :My.Little.Server 004 sender My.Little.Server sable-0.1.0-15f35c80a72c71a4796c5a2e04055817d989c3cb ioZ ntsim bqeIkov
1740592607.798 S -> 2: :My.Little.Server 005 sender EXCEPTS INVEX FNC UTF8ONLY MONITOR=64 CASEMAPPING=ascii CLIENTTAGDENY=* HOSTLEN=64 NICKLEN=15 USERLEN=10 CHANMODES=bqeI,k,,ntsim MSGREFTYPES=timestamp PREFIX=(ov)@+ :are supported by this server
1740592607.798 S -> 2: :My.Little.Server 422 sender :MOTD File is missing
1740592607.798 S -> 2: :sender!username@localhost MODE sender +
1740592607.798 S -> 2: :My.Little.Server NOTICE sender :The network is currently running in debug mode. Do not send any sensitive information such as passwords.
1740592607.798 2 -> S: PING foo
1740592608.604 2 -> S: PING synchronize414.391973892
1740592608.604 S -> 2: :My.Little.Server PONG My.Little.Server :foo
1740592608.605 S -> 2: :My.Little.Server PONG My.Little.Server :synchronize414.391973892
1740592608.605 1 -> S: CAP LS 302
1740592608.605 S -> 1: :My.Little.Server NOTICE * :*** Looking up your hostname
1740592608.605 S -> 1: :My.Little.Server CAP * LS :message-tags server-time echo-message batch labeled-response userhost-in-names away-notify account-tag multi-prefix draft/chathistory sable.libera.chat/persistent-session draft/account-registration draft/channel-rename
1740592608.606 1 -> S: CAP REQ :echo-message server-time
1740592608.606 1 -> S: nick bar
1740592608.606 1 -> S: user user 0 * realname
1740592608.606 1 -> S: CAP END
1740592608.607 S -> 1: :My.Little.Server CAP * ACK :echo-message server-time
[nothing happens]
1740592787.743 S -> 1: ERROR :Registration timed out

[spb]

Having started a new dev environment on a new Ubuntu 24.04 install, I can now reproduce this locally.

It's not ignoring the commands; all the handlers are running correctly and the new user event is submitted to the event log. For some reason the corresponding NetworkStateChange isn't making it back to the ircd code to update the connection state. Further investigation is still required, but that's the direction to look in.