Messages from IRC user sharing nickname with Matrix user don't come through at all

[Mikaela]

Describe the bug

When there is a Matrix user and IRC user by the same nickname, messages from the IRC user don't come through. This is a common scenario with Ergo IRCd which includes integrated bouncer and generally forces all connections to use the same nickname.

To Reproduce

1. Register on Ergo IRCd e.g. https://liberta.casa/gamja/ using NickServ as usual
2. Connect to the same IRCd using Matrix logging in (e.g. #irc_#libcasa.info:liberta.casa)
3. Both connections should now use the same name. Send messages from them
4. See that Matrix has no messages sent from IRC.

Expected behavior

Messages send from IRC are shown on Matrix. I know the appservice cannot pretend to be the MXID, but it could join the IRC ghost into the room (in my case @irc_Aminda:liberta.casa) to show the messages or maybe the appservice itself could show the messages (like Heisenbridge: "You said: ...)

Screenshots

Additional context

• I said I would open this issue in Duplicate messages matrix-side (due to distributed IRCds) #27 (comment) which is resolved.
• We lovingly call Matrix as Undefined as per Nicknames with slashes appear as "undefined" (RELAYMSG) #1411 due to being big users of RELAYMSG.

[Mikaela]

Attachment: IRCCloud & Heisenbridge on irc.ergo.chat:

• the less privileged here is part of the gecos and means that this account is not my primary one and thus if it got compromised through a third party service, it couldn't be used to do so nasty things as the main account which actually owns channels and has access to channels not belonging to me could.

[Half-Shot]

When there is a Matrix user and IRC user by the same nickname, messages from the IRC user don't come through.

As it stands, the bridge does not support multiple users sharing the same nickname. We treat nicknames as unique, and the bridge will not bridge anything from a user it perceives to own.

I'd imagine the solution to this would be #72, but since that issue requires a total overhaul of the inner workings, we've not got to it yet.

[Mikaela]

I don't understand #72 considering the hostmask would be identical for both Matrix and IRC user if they logged in as the same IRC account.