pgsql: Fix assertion failure in heap_vacuum_rel

Fix assertion failure in heap_vacuum_rel

Commit 7d71d3dd08 changed resetting the VacuumFailsafeActive flag to an
assertion since the flag is reset before starting vacuuming a relation.
This however failed to take recursive calls of vacuum_rel() and vacuum
of TOAST tables into consideration. Fix by reverting back to resettting
the flag.

Author: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>
Reviewed-by: Melanie Plageman <melanieplageman(at)gmail(dot)com>
Reported-by: John Naylor <john(dot)naylor(at)enterprisedb(dot)com>
Discussion: https://postgr.es/m/CAFBsxsFz=GqaG5Ens5aNgVYoV2Y+pfMUijX0ku+CCkWfALwiqg@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/4a6603cd4650a335ee38d894d7bbb452b1bf822f

Modified Files
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src/backend/access/heap/vacuumlazy.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)