pgsql: Fix incorrect logic in plpgsql for cleanup after evaluation of

Log Message:
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Fix incorrect logic in plpgsql for cleanup after evaluation of non-simple
expressions. We need to deal with this when handling subscripts in an array
assignment, and also when catching an exception. In an Assert-enabled build
these omissions led to Assert failures, but I think in a normal build the
only consequence would be short-term memory leakage; which may explain why
this wasn't reported from the field long ago.

Back-patch to all supported versions. 7.4 doesn't have exceptions, but
otherwise these bugs go all the way back.

Heikki Linnakangas and Tom Lane

Tags:
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REL8_1_STABLE

Modified Files:
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pgsql/src/pl/plpgsql/src:
pl_exec.c (r1.154.2.11 -> r1.154.2.12)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpgsql/src/pl_exec.c?r1=1.154.2.11&r2=1.154.2.12)
pgsql/src/test/regress/expected:
plpgsql.out (r1.40.2.2 -> r1.40.2.3)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/plpgsql.out?r1=1.40.2.2&r2=1.40.2.3)
pgsql/src/test/regress/sql:
plpgsql.sql (r1.34.2.2 -> r1.34.2.3)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/plpgsql.sql?r1=1.34.2.2&r2=1.34.2.3)