Fix obsolete error message (isImmutable doesn't exist).
Fix obsolete error message (isImmutable doesn't exist).

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