More clearly describe why PQinSend returns false for non-threaded libpq.
More clearly describe why PQinSend returns false for non-threaded libpq.

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