core: before returning new job path to clients, force out JobNew signals

When a client requests a new job, let's make sure we for out the JobNew
signals for it, before we return successfully from the method call.
After all we shouldn't return a path that is not announced yet, as
announcement of jobs should be considered part of the job setup.

src/core/dbus-job.c

@@ -189,6 +189,21 @@ void bus_job_send_change_signal(Job *j) {
         j->sent_dbus_new_signal = true;
 }
 
+void bus_job_send_pending_change_signal(Job *j, bool including_new) {
+        assert(j);
+
+        if (!j->in_dbus_queue)
+                return;
+
+        if (!j->sent_dbus_new_signal && !including_new)
+                return;
+
+        if (MANAGER_IS_RELOADING(j->unit->manager))
+                return;
+
+        bus_job_send_change_signal(j);
+}
+
 static int send_removed_signal(sd_bus *bus, void *userdata) {
         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
         _cleanup_free_ char *p = NULL;

src/core/dbus-job.h

@@ -12,6 +12,7 @@ int bus_job_method_cancel(sd_bus_message *message, void *job, sd_bus_error *erro
 int bus_job_method_get_waiting_jobs(sd_bus_message *message, void *userdata, sd_bus_error *error);
 
 void bus_job_send_change_signal(Job *j);
+void bus_job_send_pending_change_signal(Job *j, bool including_new);
 void bus_job_send_removed_signal(Job *j);
 
 int bus_job_coldplug_bus_track(Job *j);

src/core/dbus-unit.c

@@ -1321,6 +1321,9 @@ int bus_unit_queue_job(
         if (!path)
                 return -ENOMEM;
 
+        /* Before we send the method reply, force out the announcement JobNew for this job */
+        bus_job_send_pending_change_signal(j, true);
+
         return sd_bus_reply_method_return(message, "o", path);
 }