This was introduced in 232d2612fe which
tries to split a line by spaces and then tries splitted[1] and
splitted[2] which will cause a SIGABRT if the line isn't actually that
long.
This also uses the 4th argument to the 301 line to determine if this
message is because we sent a message to ourselfs. Previously the 3rd
option was used, which is always our own nick. This was resulting in any
301 line being halted.