In the link included in my previous post on this thread, OP commented that he can't find any network supporting this feature.
In that link you explain that mIRC does not check for any status (op etc) to hide the key, if the key received is '*', mIRC hides it.
But here mIRC receives '*' as the key but instead of hiding it, it display the previously set key.
So there is more going on in the code besides mIRC hiding the key if it's '*', and if showing the previously set key in the channel central is not a feature, it's a bug.
I agree with everything that has been said on that old thread, mIRC should never have taken the liberty to hide the key like that, it's not in the rfc and there was no way to identify if the server supported it. So if you eventually can't find network supporting that feature, I would be all for getting rid of it.
Some observations:
freenode:
-> orwell.freenode.net MODE # +k test
<- :Ouims!Wims@AMontsouris-158-1-8-167.w92-151.abo.wanadoo.fr MODE # +k test
-> orwell.freenode.net MODE # -k ??
<- :Ouims!Wims@AMontsouris-158-1-8-167.w92-151.abo.wanadoo.fr MODE # -k *
swiftirc (same result on a different unrealircd network):
-> conclave.il.us.SwiftIRC.net MODE # +k test
<- :Ouims!Wims@simple.mIRC.user MODE # +k test
-> conclave.il.us.SwiftIRC.net MODE # -k ??
<- :Ouims!Wims@simple.mIRC.user MODE # -k test
On all of them, mIRC behaves the same and pull the previously set key. Like I said, certainly this behavior is related to the feature which hides the key if it's '*', but that's not what is being reported here.