features3.js fails on countWriteBacks

 m30001| Sun Mar 25 16:33:45 [conn4] command admin.$cmd command: { fsync: 1 } ntoreturn:1 keyUpdates:0 reslen:51 2154ms

assert: [1] != [2] are not equal : with all

Error("Printing Stack Trace")@:0

()@src/mongo/shell/utils.js:37

("[1] != [2] are not equal : with all")@src/mongo/shell/utils.js:58

(1,2,"with all")@src/mongo/shell/utils.js:84

@/mnt/home/buildbot/slave/Linux_64bit/mongo/jstests/sharding/features3.js:139

Sun Mar 25 16:33:45 uncaught exception: [1] != [2] are not equal : with all

failed to load: /mnt/home/buildbot/slave/Linux_64bit/mongo/jstests/sharding/features3.js