pgsql: Fix minor bug in XLogFileRead() that accidentally worked.

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

Branch
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REL9_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/df09dbbcaa546350a78ce9f096b872fa3a28cafb

Modified Files
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src/backend/access/transam/xlog.c |    5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)