Fix minor bug in XLogFileRead() that accidentally worked. Cascading replication copied the incoming file into pg_xlog but didn't set path correctly, so the first attempt to open file failed causing it to loop around and look for file in pg_xlog. So the earlier coding worked, but accidentally rather than by design.
Fix minor bug in XLogFileRead() that accidentally worked.
Cascading replication copied the incoming file into pg_xlog but
didn't set path correctly, so the first attempt to open file failed
causing it to loop around and look for file in pg_xlog. So the
earlier coding worked, but accidentally rather than by design.

Spotted by Fujii Masao, fix by Fujii Masao and Simon Riggs

snaga/postgres-xl,kmjungersen/PostgresXL,postmind-net/postgres-xl,postmind-net/postgres-xl,arcivanov/postgres-xl,snaga/postgres-xl,postmind-net/postgres-xl,postmind-net/postgres-xl,arcivanov/postgres-xl,snaga/postgres-xl,arcivanov/postgres-xl,kmjungersen/PostgresXL,arcivanov/postgres-xl,arcivanov/postgres-xl,postmind-net/postgres-xl,snaga/postgres-xl,kmjungersen/PostgresXL,arcivanov/postgres-xl,kmjungersen/PostgresXL,snaga/postgres-xl,kmjungersen/PostgresXL