Fix bug in the new B-tree incomplete-split code.
Fix bug in the new B-tree incomplete-split code.

Forgot to update LSN of left sibling's page, when creating a new root.
I fixed this for regular insertions and page splits earlier, but missed
new root creation.

jmcatamney/gpdb,lisakowen/gpdb,jmcatamney/gpdb,lisakowen/gpdb,ashwinstar/gpdb,ovr/postgres-xl,xinzweb/gpdb,50wu/gpdb,pavanvd/postgres-xl,pavanvd/postgres-xl,lisakowen/gpdb,adam8157/gpdb,Postgres-XL/Postgres-XL,oberstet/postgres-xl,Postgres-XL/Postgres-XL,adam8157/gpdb,oberstet/postgres-xl,greenplum-db/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,yazun/postgres-xl,greenplum-db/gpdb,Postgres-XL/Postgres-XL,techdragon/Postgres-XL,50wu/gpdb,adam8157/gpdb,zeroae/postgres-xl,ovr/postgres-xl,yazun/postgres-xl,50wu/gpdb,50wu/gpdb,oberstet/postgres-xl,ovr/postgres-xl,xinzweb/gpdb,adam8157/gpdb,50wu/gpdb,ashwinstar/gpdb,lisakowen/gpdb,jmcatamney/gpdb,techdragon/Postgres-XL,pavanvd/postgres-xl,greenplum-db/gpdb,zeroae/postgres-xl,greenplum-db/gpdb,jmcatamney/gpdb,lisakowen/gpdb,oberstet/postgres-xl,greenplum-db/gpdb,oberstet/postgres-xl,pavanvd/postgres-xl,zeroae/postgres-xl,50wu/gpdb,Postgres-XL/Postgres-XL,xinzweb/gpdb,zeroae/postgres-xl,50wu/gpdb,adam8157/gpdb,Postgres-XL/Postgres-XL,zeroae/postgres-xl,greenplum-db/gpdb,50wu/gpdb,pavanvd/postgres-xl,ashwinstar/gpdb,greenplum-db/gpdb,yazun/postgres-xl,xinzweb/gpdb,techdragon/Postgres-XL,lisakowen/gpdb,ashwinstar/gpdb,xinzweb/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,ovr/postgres-xl,ashwinstar/gpdb,jmcatamney/gpdb,lisakowen/gpdb,xinzweb/gpdb,xinzweb/gpdb,adam8157/gpdb,xinzweb/gpdb,ashwinstar/gpdb,techdragon/Postgres-XL,adam8157/gpdb,adam8157/gpdb,lisakowen/gpdb,techdragon/Postgres-XL,ashwinstar/gpdb,yazun/postgres-xl,greenplum-db/gpdb,yazun/postgres-xl,ovr/postgres-xl