SERVER-15235 regular expressions with the '|' character must be classified as simple
SERVER-16036 change DBQueryQuery.count() shell helper to return the explain result rather than a cursor
SERVER-15917 fix explain of write commands against a non-existent database
SERVER-15958 initialize IndexScanStats fields isMultiKey and indexName on IndexScan construction
SERVER-15988 fix dead code in CachedPlanStage
SERVER-16052 fix $explain queries for clusters with shards at version 2.6 or earlier