fix padding_idx of RoBERTa model

transformers/modeling_roberta.py

@@ -43,6 +43,9 @@ class RobertaEmbeddings(BertEmbeddings):
     def __init__(self, config):
         super(RobertaEmbeddings, self).__init__(config)
         self.padding_idx = 1
+        self.word_embeddings = nn.Embedding(config.vocab_size, config.hidden_size, padding_idx=self.padding_idx)
+        self.position_embeddings = nn.Embedding(config.max_position_embeddings, config.hidden_size,
+                                                padding_idx=self.padding_idx)
 
     def forward(self, input_ids, token_type_ids=None, position_ids=None):
         seq_length = input_ids.size(1)