Some test fail with this patch when a MatchAllDocQuery is used, e.g. TestSimpleExplanations.testMA1. skipTo() tries to get the delete bit for a negative document, which throws an Exception of course. This happens for a searcher that contains a MultiReader created by QueryUtils.wrapUnderlyingReader().
I assume this is related to the change I made in QueryUtils. I need to spend some more time to figure out what exactly leads to this exception. Maybe I'm doing something silly here - I'm still catching up on some changes, such as the out-of-order scoring changes.
I can't work on this till Monday, so anyone familiar with these tests feel free to take a look!