Chances are probably 0 that we won't have failures
or that we'd have 100% categorization rates, which
probably mean if we don't get any failures the
default ALL_FAILS_QUERY is broken, which can easily
happen:
I208675c2258b6c635925c7b9ea9fae5afd000565
This logs a warning if a group yields no failures
based on the default ALL_FAILS_QUERY.
Change-Id: Ib2c12b1fc276389297cf4ac15775e6b2da828fdd