In pg_upgrade, fix bug where no users were dumped in pg_dumpall binary-upgrade mode;  instead only skip dumping the current user.
In pg_upgrade, fix bug where no users were dumped in pg_dumpall
binary-upgrade mode;  instead only skip dumping the current user.

This bug was introduced in during the removal of split_old_dump().  Bug
discovered during local testing.

greenplum-db/gpdb,greenplum-db/gpdb,adam8157/gpdb,pavanvd/postgres-xl,greenplum-db/gpdb,50wu/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,adam8157/gpdb,xinzweb/gpdb,jmcatamney/gpdb,yazun/postgres-xl,jmcatamney/gpdb,yazun/postgres-xl,xinzweb/gpdb,ashwinstar/gpdb,adam8157/gpdb,jmcatamney/gpdb,zeroae/postgres-xl,pavanvd/postgres-xl,Postgres-XL/Postgres-XL,50wu/gpdb,oberstet/postgres-xl,adam8157/gpdb,lisakowen/gpdb,xinzweb/gpdb,adam8157/gpdb,lisakowen/gpdb,50wu/gpdb,ovr/postgres-xl,ovr/postgres-xl,greenplum-db/gpdb,50wu/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,lisakowen/gpdb,ovr/postgres-xl,ashwinstar/gpdb,techdragon/Postgres-XL,pavanvd/postgres-xl,oberstet/postgres-xl,adam8157/gpdb,Postgres-XL/Postgres-XL,yazun/postgres-xl,zeroae/postgres-xl,Postgres-XL/Postgres-XL,techdragon/Postgres-XL,ashwinstar/gpdb,Postgres-XL/Postgres-XL,lisakowen/gpdb,ashwinstar/gpdb,pavanvd/postgres-xl,yazun/postgres-xl,oberstet/postgres-xl,adam8157/gpdb,ovr/postgres-xl,lisakowen/gpdb,50wu/gpdb,ovr/postgres-xl,xinzweb/gpdb,jmcatamney/gpdb,xinzweb/gpdb,xinzweb/gpdb,Postgres-XL/Postgres-XL,yazun/postgres-xl,lisakowen/gpdb,techdragon/Postgres-XL,ashwinstar/gpdb,xinzweb/gpdb,pavanvd/postgres-xl,oberstet/postgres-xl,ashwinstar/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,zeroae/postgres-xl,50wu/gpdb,greenplum-db/gpdb,techdragon/Postgres-XL,zeroae/postgres-xl,oberstet/postgres-xl,zeroae/postgres-xl,50wu/gpdb,lisakowen/gpdb,lisakowen/gpdb,adam8157/gpdb,xinzweb/gpdb,50wu/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,techdragon/Postgres-XL,jmcatamney/gpdb