util_test MachMessageServer.ReturnCodeNoReply: keep the child alive until the server is done

util/mach/mach_message_server_test.cc

Index: util/mach/mach_message_server_test.cc
diff --git a/util/mach/mach_message_server_test.cc b/util/mach/mach_message_server_test.cc
index 5df0a20de2b420e93e0d797ab9aea63b3e251d4a..cf2b22de089a07cccaa0bfa84a8b26386582444f 100644
--- a/util/mach/mach_message_server_test.cc
+++ b/util/mach/mach_message_server_test.cc
@@ -685,6 +685,7 @@ TEST(MachMessageServer, ReturnCodeNoReply) {
   TestMachMessageServer::Options options;
   options.server_mig_retcode = MIG_NO_REPLY;
   options.client_expect_reply = false;
+  options.child_wait_for_parent_pipe = true;
   TestMachMessageServer test_mach_message_server(options);
   test_mach_message_server.Test();
 }