Fix density sample (#21506)

python/paddle/fluid/layers/detection.py

@@ -1889,9 +1889,9 @@ def density_prior_box(input,
                 fetch_list=[box,var],
                 return_numpy=True)
 
-	    print(mask_out.shape)
+            # print(box_out.shape)
             # (1134, 4)
-            print(z_out.shape)
+            # print(var_out.shape)
             # (1134, 4)
 
 
@@ -1909,9 +1909,9 @@ def density_prior_box(input,
                     fixed_ratios=[1.],
                     clip=True)
 
-    		print(box.shape)
+                # print(box.shape)
                 # [6L, 9L, 21L, 4L]
-		print(var.shape)
+                # print(var.shape)
                 # [6L, 9L, 21L, 4L]
 
     """