tests: wait for xtables lock in builder cache registry rules

Author: cursoragent

integration/builder_cache_linux_test.go

@@ -181,9 +181,9 @@ func startBuildRegistry(t *testing.T, gateway, bridge string, p *paths.Paths, im
 	t.Cleanup(func() { _ = server.Close() })
 	port := strconv.Itoa(listener.Addr().(*net.TCPAddr).Port)
 	firewallArgs := []string{"INPUT", "-i", bridge, "-p", "tcp", "--dport", port, "-j", "ACCEPT"}
-	output, err := exec.Command("iptables", append([]string{"-I"}, firewallArgs...)...).CombinedOutput()
+	output, err := exec.Command("iptables", append([]string{"-w", "5", "-I"}, firewallArgs...)...).CombinedOutput()
 	require.NoErrorf(t, err, "allow registry traffic: %s", output)
-	t.Cleanup(func() { _ = exec.Command("iptables", append([]string{"-D"}, firewallArgs...)...).Run() })
+	t.Cleanup(func() { _ = exec.Command("iptables", append([]string{"-w", "5", "-D"}, firewallArgs...)...).Run() })
 	return net.JoinHostPort(gateway, port), string(certPEM)
 }