pgsql: plug dblink resource leak dblink generates orphaned connections

Log Message:
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plug dblink resource leak

dblink generates orphaned connections when called with a connection string,
fail_on_error = true, and an ERROR occurs. Discovery and patch by
Tatsuhito Kasahara. Introduced in 8.4.

Tags:
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REL8_4_STABLE

Modified Files:
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pgsql/contrib/dblink:
dblink.c (r1.82 -> r1.82.2.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/dblink/dblink.c?r1=1.82&r2=1.82.2.1)