PA: bug fixes for case when we need to spill.

Change-Id: I8abea0c448ed654ff465558b78f4fb8489c39dd4
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4189
Tested-by: jenkins
Reviewed-by: Nong Li <nong@cloudera.com>
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4261
Tested-by: Nong Li <nong@cloudera.com>