pgsql: Turn "check" into assertion

Turn "check" into assertion

In commit 1813f951cad5, I mistakenly assumed that one particular
function named CheckSomething() checks Something. It doesn't, it merely
return the state to check. Fix by adding the necessary Assert() call.

Good chance to add trailers for commit 1813f951cad5:
Reviewed-by: Manuel Reyes Bravo <manuelreyesbravo(at)gmail(dot)com>
Reviewed-by: Antonin Houska <ah(at)cybertec(dot)at>
Reviewed-by: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>

Backpatch-through: 19
Discussion: https://postgr.es/m/CAA-aLv5MF6BLL+BWvix2Yw+CBardtH43AofPReQunhDZPNBtuA@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/6dc3fd90f126fa409eac51a4182ee09b9d63c16c

Modified Files
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src/backend/commands/repack.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)