HIVE-6845 : TestJdbcDriver.testShowRoleGrant can fail if TestJdbcDriver/TestJdbcDriver2 run together (Jason Dere via Thejas Nair)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1585813 13f79535-47bb-0310-9956-ffa450edef68