mono/mono — pull request #591 by Adeath56 (2013-03-04 17:16:24+00:00)
Title: Patch 1

Reporting "Timeout session optimization" of the master source correct a
NullReferenceException when ResetItemTimeout() is called.
i.e. https://bugzilla.xamarin.com/show_bug.cgi?id=925

=> in ResetItemTimeout()
cache.Remove (CacheId); call OnSessionRemoved() what do the item.Dispose(),
then InsertSessionItem (inProcItem, itemTimeout, CacheId); insert item with a null rwlock

So all the next requests crash with the GetItemInternal() :
nullReferenceException on
"if (item.rwlock.TryEnterUpgradeableReadLock (lockAcquireTimeout))"