fix bug in Pad transform (PaddlePaddle#2569)

Author: will-jl944

ppdet/data/transform/operators.py

@@ -1845,7 +1845,8 @@ def __init__(self,
         assert pad_mode in [
             -1, 0, 1, 2
         ], 'currently only supports four modes [-1, 0, 1, 2]'
-        assert pad_mode == -1 and offsets, 'if pad_mode is -1, offsets should not be None'
+        if pad_mode == -1:
+            assert offsets, 'if pad_mode is -1, offsets should not be None'
 
         self.size = size
         self.size_divisor = size_divisor
@@ -1912,7 +1913,7 @@ def apply(self, sample, context=None):
                 im_h < h and im_w < w
             ), '(h, w) of target size should be greater than (im_h, im_w)'
         else:
-            h = np.ceil(im_h // self.size_divisor) * self.size_divisor
+            h = np.ceil(im_h / self.size_divisor) * self.size_divisor
             w = np.ceil(im_w / self.size_divisor) * self.size_divisor
 
         if h == im_h and w == im_w: