Second try at fixing no-room-to-move-down PANIC in compact_fsm_storage. Ward's report that it can still happen in RC2 forces me to realize that this is not a can't-happen condition after all, and that the compaction code had better cope rather than panicking.
Second try at fixing no-room-to-move-down PANIC in compact_fsm_storage.
Ward's report that it can still happen in RC2 forces me to realize that
this is not a can't-happen condition after all, and that the compaction
code had better cope rather than panicking.

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