Fix minus sign

Author: feynmanliang

labelbox/exporters/pascal_voc_writer/__init__.py

@@ -42,8 +42,8 @@ def add_object(self, name, xy_coords):
             # quantize up to 1 px off to bounding boxes
             if abs(x_points[0] - x_points[1]) < 1 \
                     and abs(x_points[2] - x_points[3]) < 1 \
-                    and abs(y_points[0] == y_points[1]) < 1 \
-                    and abs(y_points[2] == y_points[3]) < 1:
+                    and abs(y_points[0] - y_points[1]) < 1 \
+                    and abs(y_points[2] - y_points[3]) < 1:
                 x_points[0] = x_points[1]
                 x_points[2] = x_points[3]
                 label_type = 'bndbox'