Fix LearnedPositionalEmbedding

fairseq/modules/learned_positional_embedding.py

@@ -22,7 +22,6 @@ class LearnedPositionalEmbedding(nn.Embedding):
     def __init__(self, num_embeddings, embedding_dim, padding_idx, left_pad):
         super().__init__(num_embeddings, embedding_dim, padding_idx)
         self.left_pad = left_pad
-        self.register_buffer('range_buf', None)
         self._is_incremental_eval = False
 
     def incremental_eval(self, mode=True):
@@ -44,7 +43,7 @@ class LearnedPositionalEmbedding(nn.Embedding):
 
     def make_positions(self, input):
         """Replace non-padding symbols with their position numbers."""
-        if self.range_buf is None:
+        if not hasattr(self, 'range_buf'):
             self.range_buf = input.new()
         seqlen = input.size(1)
         if self.range_buf.numel() < seqlen: