pgsql: Fix bug in brin_minmax_multi_union

Fix bug in brin_minmax_multi_union

When calling sort_expanded_ranges() we need to remember the return
value, because the function sorts and also deduplicates the ranges. So
the number of ranges may decrease. brin_minmax_multi_union failed to do
that, which resulted in crashes due to bogus ranges (equal minval/maxval
but not marked as compacted).

Reported-by: Jaime Casanova
Discussion: https://postgr.es/m/20210404052550.GA4376%40ahch-to

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d9c5b9a9eeb9e3061ae139e0e564ce5358c94001

Modified Files
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src/backend/access/brin/brin_minmax_multi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)