revert bug of pr #2115 (#2124)

* revert bug of pr #2115

* fix yaml

ppcls/configs/PULC/vehicle_attribute/PPLCNet_x1_0_distillation.yaml

@@ -22,6 +22,7 @@ Arch:
   # if not null, its lengths should be same as models
   pretrained_list:
   # if not null, its lengths should be same as models
+  infer_model_name: "Student"
   freeze_params_list:
   - True
   - False

ppcls/data/dataloader/multilabel_dataset.py

@@ -42,7 +42,7 @@ class MultiLabelDataset(CommonDataset):
 
                 self.labels.append(labels)
                 assert os.path.exists(self.images[-1])
-        if self.label_ratio:
+        if self.label_ratio is not False:
             return np.array(self.labels).mean(0).astype("float32")
 
     def __getitem__(self, idx):
@@ -53,7 +53,7 @@ class MultiLabelDataset(CommonDataset):
                 img = transform(img, self._transform_ops)
             img = img.transpose((2, 0, 1))
             label = np.array(self.labels[idx]).astype("float32")
-            if self.label_ratio:
+            if self.label_ratio is not False:
                 return (img, np.array([label, self.label_ratio]))
             else:
                 return (img, label)