While backporting batch #9, query_stats_agg_key.js fails with withQueryStatsEnabled shardingTest. From my investigations so far, it seems that the request is registered but is not being written (writeQueryStats is never called for the command). 

https://github.com/10gen/mongo/tree/erinzhu001/query_stats_backport_batch_9
for the branch that has the changes necessary to replicate this issue. 

buildscripts/resmoke.py run --suites=no_passthrough jstests/noPassthrough/queryStats/query_stats_agg_key.js  --additionalFeatureFlags=featureFlagQueryStats