Add comment to explain why O_EXCL and O_TRUNC can be ignored in openFlagsToCreateFileFlags() in certain cases.
Add comment to explain why O_EXCL and O_TRUNC can be ignored in
openFlagsToCreateFileFlags() in certain cases.

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