Fixup for b84a6dafbf triggering assert failure in LLVM debug builds.
Fixup for b84a6dafbf triggering assert failure in LLVM debug builds.

Author: Andres Freund

adam8157/gpdb,lisakowen/gpdb,lisakowen/gpdb,xinzweb/gpdb,xinzweb/gpdb,50wu/gpdb,50wu/gpdb,50wu/gpdb,lisakowen/gpdb,greenplum-db/gpdb,lisakowen/gpdb,lisakowen/gpdb,xinzweb/gpdb,xinzweb/gpdb,xinzweb/gpdb,50wu/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,lisakowen/gpdb,adam8157/gpdb,adam8157/gpdb,adam8157/gpdb,50wu/gpdb,xinzweb/gpdb,greenplum-db/gpdb,adam8157/gpdb,adam8157/gpdb,greenplum-db/gpdb,50wu/gpdb,xinzweb/gpdb,adam8157/gpdb,xinzweb/gpdb,lisakowen/gpdb,adam8157/gpdb,50wu/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,50wu/gpdb,lisakowen/gpdb