pgsql: Fix PHJ match bit initialization.

Fix PHJ match bit initialization.

Hash join tuples reuse the HOT status bit to indicate match status
during hash join execution. Correct reuse requires clearing the bit in
all tuples. Serial hash join and parallel multi-batch hash join do so
upon inserting the tuple into the hashtable. Single batch parallel hash
join and batch 0 of unexpected multi-batch hash joins forgot to do this.

It hadn't come up before because hashtable tuple match bits are only
used for right and full outer joins and parallel ROJ and FOJ were
unsupported. 11c2d6fdf5 introduced support for parallel ROJ/FOJ but
neglected to ensure the match bits were reset.

Author: Melanie Plageman <melanieplageman@gmail.com>
Reported-by: Richard Guo <guofenglinux@gmail.com>
Discussion: https://postgr.es/m/flat/CAMbWs48Nde1Mv%3DBJv6_vXmRKHMuHZm2Q_g4F6Z3_pn%2B3EV6BGQ%40mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/558c9d75fe3b38508296840e606737c664fc3b70

Modified Files
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src/backend/executor/nodeHash.c         |  1 +
src/test/regress/expected/join_hash.out | 37 +++++++++++++++++++++++++++++++++
src/test/regress/sql/join_hash.sql      | 28 ++++++++++++++++++++++++-
3 files changed, 65 insertions(+), 1 deletion(-)