HIVE-6635 : Heartbeats are not being sent when DbLockMgr is used and an operation holds locks (Alan Gates via Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/branch-0.13@1580941 13f79535-47bb-0310-9956-ffa450edef68