Don't just assume that the next port is free; it might not be, or
if we're really unlucky it might even be out of the TCP range.
Do it honestly with two get_free_port() calls instead.
This is surely a pretty low-probability problem, but I think it
explains a buildfarm failure seen today, so let's fix it.
Back-patch to v11 where this script was added.
Discussion: https://postgr.es/m/25124.
1568052346@sss.pgh.pa.us
my $ldap_conf = "${TestLib::tmp_check}/ldap.conf";
my $ldap_server = 'localhost';
my $ldap_port = get_free_port();
-my $ldaps_port = $ldap_port + 1;
+my $ldaps_port = get_free_port();
my $ldap_url = "ldap://$ldap_server:$ldap_port";
my $ldaps_url = "ldaps://$ldap_server:$ldaps_port";
my $ldap_basedn = 'dc=example,dc=net';