JakeWharton/ActionBarSherlock — pull request #218 by MarcusWolschon (2012-02-06 13:34:19+00:00)
Title: 4.0 wip

Your MenuWrapper returned NULL on Android 4.0.x for the UP MenuItem (itemID==android.R.id.home).
This resulted in onOptionItemSelected being called with NULL.
I left the 2 log-statements in there to show when exactly this happens and also added some code to make this bullet proof in case a future Android version changes it's behavior slightly (e.g. comparison by instance instead of itemID of MenuItems failing).