Fix broken Assert() introduced by 8e9a16ab8f7f0e58
Fix broken Assert() introduced by 8e9a16ab8f7f0e58

Don't assert MultiXactIdIsRunning if the multi came from a tuple that
had been share-locked and later copied over to the new cluster by
pg_upgrade.  Doing that causes an error to be raised unnecessarily:
MultiXactIdIsRunning is not open to the possibility that its argument
came from a pg_upgraded tuple, and all its other callers are already
checking; but such multis cannot, obviously, have transactions still
running, so the assert is pointless.

Noticed while investigating the bogus pg_multixact/offsets/0000 file
left over by pg_upgrade, as reported by Andres Freund in
http://www.postgresql.org/message-id/20140530121631.GE25431@alap3.anarazel.de

Backpatch to 9.3, as the commit that introduced the buglet.

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