IMPALA-2496: Fix flaky test in test_insert_behaviour.py
IMPALA-2496: Fix flaky test in test_insert_behaviour.py

Change-Id: I1c7f0206ba703e7c5766c79f0331724eb551893f
Reviewed-on: http://gerrit.cloudera.org:8080/1203
Reviewed-by: Dan Hecht <20ebd99959f0f6e5dcb0fc319b4d8ef53a16b5fb@cloudera.com>
Tested-by: Internal Jenkins

michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala