[closed] cls token in XLM
## 🐛 Bug

The CLS token in XLM should be \<s\> rather than \</s\> in the current repo.
Here is the XLM's original BOS_WORD:
https://github.com/facebookresearch/XLM/blob/master/src/data/dictionary.py#L17

In the transformers' repo, cls_token is set to \</s\>.
https://github.com/huggingface/transformers/blob/master/src/transformers/tokenization_xlm.py#L562

And the cls token is used as the BOS token. This is not the same as the original one.
https://github.com/huggingface/transformers/blob/master/src/transformers/tokenization_xlm.py#L824


Model I am using (Bert, XLNet....): XLM

I find that the first token in the original XLM is indeed using \</s\> rather than \<s\>. 