Revert r86872: Breaks LiquidThreads page moves with the below failure. Threads are...

Revert r86872: Breaks LiquidThreads page moves with the below failure. Threads are lost and nowhere to be found any more.

[25-Apr-2011 18:12:45] /wiki/Special:MoveThread/Thread:User_talk:Siebrand/test/One_new_message: Exception: MWNamespace::getTalk does not make any sense for given namespace -1
#0 /www/w/includes/Namespace.php(81): MWNamespace::isMethodValidFor(-1, 'MWNamespace::ge...')
#1 /www/w/includes/WatchedItem.php(73): MWNamespace::getTalk(-1)
#2 /www/w/includes/User.php(2304): WatchedItem->addWatch()
#3 /www/w/includes/actions/WatchAction.php(53): User->addWatch(Object(Title))
#4 /www/w/includes/Action.php(376): WatchAction->onView()
#5 /www/w/extensions/LiquidThreads/classes/Thread.php(115): FormlessAction->execute()
#6 /www/w/extensions/LiquidThreads/classes/Thread.php(435): Thread::create(Object(Article), Object(Article), NULL, 1, 'One new message')
#7 /www/w/extensions/LiquidThreads/classes/Thread.php(414): Thread->leaveTrace('move test', Object(Title), Object(Title))
#8 /www/w/extensions/LiquidThreads/pages/SpecialMoveThread.php(107): Thread->moveToPage(Object(Title), 'move test', true)
#9 [internal function]: SpecialMoveThread->trySubmit(Array)
#10 /www/w/includes/HTMLForm.php(279): call_user_func(Array, Array)
#11 /www/w/includes/HTMLForm.php(228): HTMLForm->trySubmit()
#12 /www/w/includes/HTMLForm.php(242): HTMLForm->tryAuthorizedSubmit()
#13 /www/w/extensions/LiquidThreads/pages/ThreadActionPage.php(37): HTMLForm->show()
#14 /www/w/includes/SpecialPageFactory.php(459): ThreadActionPage->execute('Thread:User_tal...')
#15 /www/w/includes/Wiki.php(252): SpecialPageFactory::executePath(Object(Title), Object(RequestContext))
#16 /www/w/includes/Wiki.php(98): MediaWiki->handleSpecialCases()
#17 /www/w/index.php(145): MediaWiki->performRequestForTitle(NULL)
#18 {main}