See T19342 for original bug which was fixed incorrectly.
Currently LogPager::enforceActionRestrictions() and LogPager::enforcePerformerRestrictions() are reversed (The former does the latter and the latter does the former). This means that the wrong types of restrictions were being enforced. Additionally LogPager::limitType is not calling enforceActionRestrictions, which it should.
So basically, if you searched for a specific log type, it would include log entries of that type where the log type was revision deleted. If you searched for a specific log title, it would filter out log entries where the author was deleted (instead of type like it was supposed to). If you searched for a specific author, it would filter out entries where the type is deleted (instead of author).
[discovered while looking into T187638]