Buildbot sharding suite: http://buildlogs.mongodb.org/build/50345026d2a60f449d00091a/test/5034ade0d2a60f2e22000e7c/

jstests/sharding/read_pref.js stops 4 out of 5 nodes in a replica set, leaving just a secondary running. But it tests that it has reached this state by looking at the state of only one of the nodes that it has stopped (and the one it left running), so the test for 'readPref( "nearest" )' may try to use a secondary that has been stopped. The test should wait until mongos sees all stopped nodes as down before testing "nearest".