Fix prefix parsing

[emersonveenstra]

The regex matcher tried to specify specific characters for a nick,
which doesn't work anymore, especially with things like RELAYMSG

Signed off by Emerson Veenstra [email protected]

[emersonveenstra]

I guess i need to fix some tests 😬

[tadzik]

The regex matcher tried to specify specific characters for a nick,

Right, it's currently (on master) not very future proof. Have you considered using a broader character class instead, similarly to how the latter part of the current regex does, something like /^([^!]*)(!([^@]+)@(.*))?$/? Not sure if that's more readable in practice (shame that JS regexes don't have an /x modifier), but would save us looking at the code and trying to figure out if it doesn't have an accidental off-by-one ;)

In any case, can we get some tests for the // I don't think we'll get here bit, just in case? :)

[aabluedragon]

Just stumbled upon it myself, when users choose a nick such as (-_-) it would leave an entry in the nick list of matrix-org-irc which would not clean up until you restart the process.
After merging this PR into my own branch, the problem is gone.