Re: pgsql: Fix search_path to a safe value during maintenance operations.

Here is a new version of the patch that I think is ready for commit (except
it still needs a catversion bump).  The only real difference from v1 is in
AdjustUpgrade.pm.  From my cross-version pg_upgrade testing, I believe we
can remove the other "privilege-set discrepancy" rule as well.

Since MAINTAIN will no longer exist in v16, we'll also need the following
change applied to v17devel:

    diff --git a/src/test/perl/PostgreSQL/Test/AdjustUpgrade.pm b/src/test/perl/PostgreSQL/Test/AdjustUpgrade.pm
    index 843f65b448..d435812c06 100644
    --- a/src/test/perl/PostgreSQL/Test/AdjustUpgrade.pm
    +++ b/src/test/perl/PostgreSQL/Test/AdjustUpgrade.pm
    @@ -274,7 +274,7 @@ sub adjust_old_dumpfile
             $dump = _mash_view_qualifiers($dump);
         }
     
    -    if ($old_version >= 14 && $old_version < 16)
    +    if ($old_version >= 14 && $old_version < 17)
         {
             # Fix up some privilege-set discrepancies.
             $dump =~

On Thu, Jul 06, 2023 at 10:20:04AM -0700, Nathan Bossart wrote:
> On Thu, Jul 06, 2023 at 12:55:14AM -0700, Jeff Davis wrote:
>> Also remember to bump the catversion. Other than that, it looks good to
>> me.
> 
> Will do.

Since we are only reverting from v16, the REL_16_STABLE catversion will be
bumped ahead of the one on master.  AFAICT that is okay, but there is also
a chance that someone bumps the catversion on master to the same value.
I'm not sure if this is problem is worth worrying about, but I thought I'd
raise it just in case.  I could bump the catversion on master to the
following value to help prevent this scenario, but I'm not wild about
adding unnecessary catversion bumps.

-- 
Nathan Bossart
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