Re: libpq environment variables in the server

Looks good.

On Thu, Mar 14, 2019 at 12:06:45PM +0100, Peter Eisentraut wrote:
> +	# Temporarily unset PGAPPNAME so that the server doesn't inherit
> +	# it.  Otherwise this could affect libpqwalreceiver connections in
> +	# confusing ways.
> +	my $save_pgappname = $ENV{PGAPPNAME};
> +	delete $ENV{PGAPPNAME};
> +
>  	# Note: We set the cluster_name here, not in postgresql.conf (in
>  	# sub init) so that it does not get copied to standbys.
>  	my $ret = TestLib::system_log('pg_ctl', '-D', $self->data_dir, '-l',
>  		$self->logfile, '-o', "--cluster-name=$name", 'start');
>  
> +	$ENV{PGAPPNAME} = $save_pgappname;
> +

I consider the following style more idiomatic:

 {
     local %ENV;
     delete $ENV{PGAPPNAME};
     ...
 }

I'm okay with the way you've written it, though.