Re: tweak to a few index tests to hits ambuildempty() routine.

After analyzing this, I found out why we don't reach that Assert but we 
have coverage shown - firstly, it reached via another test, vacuum; 
secondly, it depends on the gcc optimization flag. We reach that Assert 
only when using -O0.
If we build with -O2 or -Og that function is not reached (due to 
different results of the heap_prune_satisfies_vacuum() check inside 
heap_page_prune()).
But as  the make checks mostly (including the buildfarm testing) 
performed  with -O2/-Og, it looks like that after 4fb5c794e5 we have 
lost the coverage provided by the 4c51a2d1e4.

Amul Sul писал 2022-09-14 14:28:
> On Wed, Sep 14, 2022 at 12:16 PM <a.kozhemyakin@postgrespro.ru> wrote:
>> 
>> I still wonder, if assert doesn't catch why that place is marked as
>> covered here?
>> https://coverage.postgresql.org/src/backend/access/gin/ginvacuum.c.gcov.html
>> 
> 
> Probably other tests cover that.
> 
> Regards,
> Amul