core: in execute, soft fail setting Nice priority, when permissions a…

src/core/execute.c

@@ -2509,11 +2509,18 @@ static int exec_child(
                 }
         }
 
-        if (context->nice_set)
-                if (setpriority(PRIO_PROCESS, 0, context->nice) < 0) {
+        if (context->nice_set) {
+                r = setpriority(PRIO_PROCESS, 0, context->nice);
+                if (r == -EPERM || r == -EACCES) {
+                        log_open();
+                        log_unit_debug_errno(unit, r, "Failed to adjust Nice setting, assuming containerized execution, ignoring: %m");
+                        log_close();
+                } else if (r < 0) {
                         *exit_status = EXIT_NICE;
+                        *error_message = strdup("Failed to adjust Nice setting");
                         return -errno;
                 }
+        }
 
         if (context->cpu_sched_set) {
                 struct sched_param param = {