select/serial gres scheduling fix

Equivalent fix as e1a00772
for select/serial rather than select/cons_res

src/plugins/select/serial/job_test.c

@@ -127,6 +127,11 @@ uint16_t _can_job_run_on_node(struct job_record *job_ptr, bitstr_t *core_map,
 	gres_plugin_job_core_filter(job_ptr->gres_list, gres_list, test_only,
 				    core_map, core_start_bit, core_end_bit,
 				    node_ptr->name);
+	gres_cores = gres_plugin_job_test(job_ptr->gres_list,
+					  gres_list, test_only,
+					  core_map, core_start_bit,
+					  core_end_bit, job_ptr->job_id,
+					  node_ptr->name);
 
 	if ((cr_type & CR_MEMORY) && cpus) {
 		req_mem   = job_ptr->details->pn_min_memory & ~MEM_PER_CPU;
@@ -137,11 +142,6 @@ uint16_t _can_job_run_on_node(struct job_record *job_ptr, bitstr_t *core_map,
 			cpus = 0;
 	}
 
-	gres_cores = gres_plugin_job_test(job_ptr->gres_list,
-					  gres_list, test_only,
-					  core_map, core_start_bit,
-					  core_end_bit, job_ptr->job_id,
-					  node_ptr->name);
 	gres_cpus = gres_cores;
 	if (gres_cpus != NO_VAL)
 		gres_cpus *= cpus_per_core;