When one joined to a channel after someone else's autoop already sent a
challenge, the other autoop will forget it sent a challange and happily generate
a new one. This might cause bogous "incorrect password" messages.
Patch by DarthGandalf, bug found by SilverLeo (I think...).
git-svn-id: https://znc.svn.sourceforge.net/svnroot/znc/trunk@1998 726aef4b-f618-498e-8847-2d620e286838