db2 distinct call results are different from mongodb call

when pymongo call distinct against a collection, the results are
different between db2 and mongodb. Need to write different code
to make sure jenkins test which is uses mongo and db2 both will
work.

Change-Id: I714c85f840a7e906ab76130cab214249c6ee0cf3
Merge "db2 distinct call results are different from mongodb call"