ForceOverFlow style was removed from 4.2. Jake made a comment about why he removed it in one of his G+ posts.
Someone had asked him if there was a reason for removing the ForceOverflow style and he replied:
"Yes. They should have never been there in the first place and they created inconsistency across API levels. An ICS device with a hardware menu key does not show an overflow so neither should a pre-ICS device."
He also goes on to say "ActionBarSherlock's goal is consistency across API levels. This is the same reason we can't fix some fundamental bugs that appear in the ICS+ action bar."
For the full thread checkout https://plus.google.com/u/0/108284392618554783657/posts/L7nsqBiAtsk