Covers CID: 20291, 21823, 64199

A new defect has been detected and assigned to renctan in Coverity Connect.
http://coverity.mongodb.com//sourcebrowser.htm?projectId=10001#mergedDefectId=20291
The defect was flagged by checker PW.PARAMETER_HIDDEN in
file /src/mongo/s/commands_public.cpp
function None
and this ticket was created by renctan