pgsql: Recent changes to allow hash join to exit early given empty input

Log Message:
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Recent changes to allow hash join to exit early given empty input from
one child or the other had a problem: they did not leave the node in a
state that ExecReScanHashJoin would understand. In particular it would
tend to fail to reset the child plans when needed. Per report from
Mario Weilguni.

Tags:
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REL8_1_STABLE

Modified Files:
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pgsql/src/backend/executor:
nodeHashjoin.c (r1.75.2.1 -> r1.75.2.2)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/nodeHashjoin.c.diff?r1=1.75.2.1&r2=1.75.2.2)