Finally found the underlying cause of the relaynames bug.

src/irclib.py

@@ -296,7 +296,7 @@ class IrcState(IrcCommandDispatcher):
         chan.topic = msg.args[2]
 
     def doNick(self, irc, msg):
-        newNick = msg.args[0]
+        newNick = nick(msg.args[0])
         oldNick = msg.nick
         try:
             if msg.user and msg.host:

src/ircmsgs.py

@@ -79,7 +79,10 @@ class IrcMsg(object):
         self._user = user
         self._host = host
         self._command = command
+        if self.command == 'NICK':
+            self._args[0] = ircutils.nick(self._args[0])
         self._args = tuple(args)
+            
 
     prefix = property(lambda self: self._prefix)
     nick = property(lambda self: self._nick)

src/ircutils.py

@@ -235,8 +235,15 @@ def shrinkList(L, sep='', limit=425):
 class nick(str):
     """This class does case-insensitive comparisons of nicks."""
     def __init__(self, s):
+        self.original = s
         self.lowered = toLower(s)
 
+    def __repr__(self):
+        return repr(self.original)
+
+    def __str__(self):
+        return str(self.original)
+    
     def __eq__(self, s):
         try:
             return toLower(s) == self.lowered