Pidgin freezes when closing an IRC channel window

[David Barth]

Binary package hint: pidgin-libnotify

With pidgin configured this way:
[15:43] <njpatel> dbarth: right, pidgin has the ability for you to be part of an irc chat, but not have the chat window opened. When someone pings you, it opens up and you can read the log
[15:46] <njpatel> dbarth: right-click on the channel in your buddy list, and then check the "persistent" checkbox. Then, even if you close the window, it's logged in

And as reported by Neil, for reference:
[15:31] <njpatel> does anyone have the issue that, if your in a irc chat in pidgin, but the window isn't open and someone talks to you, the window that pops up with the chat cannot be closed without freezing pidgin?
[15:31] <njpatel> only on irc chats that your 'in' but the window is closed

When trying to close the window, pidgin goes into an infinite loop and freezes. The window is not closed.

With 'top' it seems that pidgin and Xorg take most of the CPU, while observing the window manager (metactiy) I can see the window title name change very rapidly.

The bug can be reproduced consistently.

The bug does not occur if the pidgin-libnotify is removed and using a double-click on the channel name to re-open the chat window.