Use a cleaner substitute for the inability to apply length() to the tail of a list.  Per private discussion with Neil.
Use a cleaner substitute for the inability to apply length() to the tail
of a list.  Per private discussion with Neil.

Quikling/gpdb,chrishajas/gpdb,cjcjameson/gpdb,Postgres-XL/Postgres-XL,atris/gpdb,yuanzhao/gpdb,randomtask1155/gpdb,0x0FFF/gpdb,ahachete/gpdb,ashwinstar/gpdb,adam8157/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,kmjungersen/PostgresXL,lintzc/gpdb,oberstet/postgres-xl,greenplum-db/gpdb,lisakowen/gpdb,adam8157/gpdb,postmind-net/postgres-xl,yazun/postgres-xl,lpetrov-pivotal/gpdb,yuanzhao/gpdb,postmind-net/postgres-xl,xuegang/gpdb,xuegang/gpdb,royc1/gpdb,xinzweb/gpdb,zeroae/postgres-xl,yuanzhao/gpdb,xuegang/gpdb,pavanvd/postgres-xl,yuanzhao/gpdb,kaknikhil/gpdb,zaksoup/gpdb,atris/gpdb,adam8157/gpdb,foyzur/gpdb,zaksoup/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,Postgres-XL/Postgres-XL,rvs/gpdb,50wu/gpdb,atris/gpdb,cjcjameson/gpdb,pavanvd/postgres-xl,randomtask1155/gpdb,techdragon/Postgres-XL,xuegang/gpdb,Chibin/gpdb,lpetrov-pivotal/gpdb,arcivanov/postgres-xl,arcivanov/postgres-xl,ahachete/gpdb,randomtask1155/gpdb,janebeckman/gpdb,royc1/gpdb,50wu/gpdb,adam8157/gpdb,rubikloud/gpdb,edespino/gpdb,edespino/gpdb,CraigHarris/gpdb,Chibin/gpdb,xinzweb/gpdb,50wu/gpdb,lisakowen/gpdb,pavanvd/postgres-xl,kaknikhil/gpdb,royc1/gpdb,snaga/postgres-xl,janebeckman/gpdb,lintzc/gpdb,oberstet/postgres-xl,Quikling/gpdb,zaksoup/gpdb,janebeckman/gpdb,50wu/gpdb,ahachete/gpdb,jmcatamney/gpdb,Chibin/gpdb,lintzc/gpdb,postmind-net/postgres-xl,lpetrov-pivotal/gpdb,edespino/gpdb,lintzc/gpdb,50wu/gpdb,CraigHarris/gpdb,janebeckman/gpdb,Chibin/gpdb,ovr/postgres-xl,tangp3/gpdb,kaknikhil/gpdb,Quikling/gpdb,zaksoup/gpdb,rvs/gpdb,Chibin/gpdb,rvs/gpdb,ashwinstar/gpdb,Postgres-XL/Postgres-XL,yuanzhao/gpdb,janebeckman/gpdb,xuegang/gpdb,CraigHarris/gpdb,lisakowen/gpdb,randomtask1155/gpdb,0x0FFF/gpdb,zeroae/postgres-xl,arcivanov/postgres-xl,cjcjameson/gpdb,kaknikhil/gpdb,ahachete/gpdb,Chibin/gpdb,lisakowen/gpdb,zeroae/postgres-xl,kaknikhil/gpdb,atris/gpdb,edespino/gpdb,foyzur/gpdb,CraigHarris/gpdb,tangp3/gpdb,CraigHarris/gpdb,lintzc/gpdb,tpostgres-projects/tPostgres,royc1/gpdb,0x0FFF/gpdb,tangp3/gpdb,kaknikhil/gpdb,yuanzhao/gpdb,adam8157/gpdb,chrishajas/gpdb,kmjungersen/PostgresXL,rubikloud/gpdb,rubikloud/gpdb,cjcjameson/gpdb,chrishajas/gpdb,janebeckman/gpdb,adam8157/gpdb,foyzur/gpdb,Quikling/gpdb,yuanzhao/gpdb,jmcatamney/gpdb,janebeckman/gpdb,50wu/gpdb,snaga/postgres-xl,adam8157/gpdb,Postgres-XL/Postgres-XL,ahachete/gpdb,xinzweb/gpdb,rvs/gpdb,Postgres-XL/Postgres-XL,Quikling/gpdb,xinzweb/gpdb,yuanzhao/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,CraigHarris/gpdb,xuegang/gpdb,atris/gpdb,0x0FFF/gpdb,tpostgres-projects/tPostgres,rvs/gpdb,zaksoup/gpdb,techdragon/Postgres-XL,royc1/gpdb,edespino/gpdb,xinzweb/gpdb,rubikloud/gpdb,rubikloud/gpdb,lisakowen/gpdb,rubikloud/gpdb,edespino/gpdb,ahachete/gpdb,rubikloud/gpdb,ovr/postgres-xl,chrishajas/gpdb,lintzc/gpdb,Chibin/gpdb,rvs/gpdb,janebeckman/gpdb,yazun/postgres-xl,arcivanov/postgres-xl,lisakowen/gpdb,rvs/gpdb,foyzur/gpdb,Quikling/gpdb,janebeckman/gpdb,xuegang/gpdb,cjcjameson/gpdb,tpostgres-projects/tPostgres,edespino/gpdb,foyzur/gpdb,0x0FFF/gpdb,xuegang/gpdb,Chibin/gpdb,ahachete/gpdb,randomtask1155/gpdb,cjcjameson/gpdb,lpetrov-pivotal/gpdb,jmcatamney/gpdb,arcivanov/postgres-xl,edespino/gpdb,atris/gpdb,royc1/gpdb,randomtask1155/gpdb,50wu/gpdb,ashwinstar/gpdb,yazun/postgres-xl,CraigHarris/gpdb,greenplum-db/gpdb,zaksoup/gpdb,xinzweb/gpdb,adam8157/gpdb,lpetrov-pivotal/gpdb,lintzc/gpdb,yazun/postgres-xl,Quikling/gpdb,arcivanov/postgres-xl,ashwinstar/gpdb,zeroae/postgres-xl,yuanzhao/gpdb,tpostgres-projects/tPostgres,janebeckman/gpdb,tpostgres-projects/tPostgres,yuanzhao/gpdb,kmjungersen/PostgresXL,tangp3/gpdb,royc1/gpdb,rvs/gpdb,oberstet/postgres-xl,Chibin/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,foyzur/gpdb,kaknikhil/gpdb,snaga/postgres-xl,kmjungersen/PostgresXL,greenplum-db/gpdb,ovr/postgres-xl,techdragon/Postgres-XL,Quikling/gpdb,randomtask1155/gpdb,postmind-net/postgres-xl,rubikloud/gpdb,chrishajas/gpdb,Quikling/gpdb,50wu/gpdb,cjcjameson/gpdb,xinzweb/gpdb,kmjungersen/PostgresXL,oberstet/postgres-xl,0x0FFF/gpdb,foyzur/gpdb,edespino/gpdb,greenplum-db/gpdb,xuegang/gpdb,edespino/gpdb,postmind-net/postgres-xl,lintzc/gpdb,tangp3/gpdb,royc1/gpdb,cjcjameson/gpdb,ovr/postgres-xl,zaksoup/gpdb,atris/gpdb,pavanvd/postgres-xl,chrishajas/gpdb,jmcatamney/gpdb,atris/gpdb,snaga/postgres-xl,rvs/gpdb,0x0FFF/gpdb,tangp3/gpdb,lintzc/gpdb,zaksoup/gpdb,ashwinstar/gpdb,lpetrov-pivotal/gpdb,CraigHarris/gpdb,kaknikhil/gpdb,chrishajas/gpdb,Chibin/gpdb,zeroae/postgres-xl,Quikling/gpdb,jmcatamney/gpdb,foyzur/gpdb,ashwinstar/gpdb,lpetrov-pivotal/gpdb,kaknikhil/gpdb,kaknikhil/gpdb,oberstet/postgres-xl,tangp3/gpdb,lisakowen/gpdb,yazun/postgres-xl,cjcjameson/gpdb,tangp3/gpdb,CraigHarris/gpdb,randomtask1155/gpdb,snaga/postgres-xl,0x0FFF/gpdb,techdragon/Postgres-XL,pavanvd/postgres-xl,lpetrov-pivotal/gpdb,chrishajas/gpdb,techdragon/Postgres-XL,greenplum-db/gpdb,rvs/gpdb,cjcjameson/gpdb,ahachete/gpdb,lisakowen/gpdb,xinzweb/gpdb,ovr/postgres-xl