[COMMITTERS] pgsql: Avoid core dump for empty prepared statement in an abortedtrans

Avoid core dump for empty prepared statement in an aborted transaction.

Brown-paper-bag bug in commit ab1f0c822: the old code here coped with
null CachedPlanSource.raw_parse_tree, the new code not so much.
Per report from Dave Cramer.

No regression test, because our core testing infrastructure doesn't
provide any easy way to exercise this path.  Fortunately, the JDBC
crew test it regularly.

Discussion: https://postgr.es/m/CADK3HH+Ug3xCysKqw_dZOnaNnytZ1Rh5yP05hjO-e4NoyRxVvA@mail.gmail.com

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/ba61a04bc7fefeee03416d9911eb825c4897c223

Modified Files
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src/backend/tcop/postgres.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)