Test::More dups standard FDs and may create FDs for other
purposes. run_mode => 0 lets us rely on FD_CLOEXEC to ensure
-imapd has enough FDs to accept all incoming connections at
the cost of higher (one-off) startup time.
my $env = { PI_CONFIG => $pi_config };
my $arg = $TEST_TLS ? [ "-limaps://$imaps_addr/?cert=$cert,key=$key" ] : [];
my $cmd = [ '-imapd', '-W0', @$arg, "--stdout=$out", "--stderr=$err" ];
-my $td = start_script($cmd, $env, { 3 => $imaps });
+
+# run_mode=0 ensures Test::More FDs don't get shared
+my $td = start_script($cmd, $env, { 3 => $imaps, run_mode => 0 });
my %ssl_opt;
if ($TEST_TLS) {
%ssl_opt = (