There's just some search fixes in this release. Important, but not especially interesting.
From the CHANGELOG:
* Several search fixes: - With postgres search: * Fixed reindexing after it broke with the previous update that eliminated a lot of unneeded extra rows in the database. * Fixed basic queries with NOT statements. * Separately, fixed using NOT with subqueries. On a somewhat complicated note, but in a way that appears to match standard Solr behavior, when doing a query like "name:chef* AND NOT (admin:true OR admin:bleh)" it works as is, but when a negated subquery is followed by another basic query statement, it needs to have extra parentheses around the NOT + subquery, like "name:chef* AND (NOT (admin:true OR admin:bleh)) AND public_key:*". A convoluted and unlikely scenario, but it could happen. - With in-memory search: * NOT + subqueries was also broken with the in-mem search. The fixes for the pg-search partially fixed it for in-mem in that it no longer made the server panic, but it was returning incorrect results. Additional work ended up being needed for in-mem search.