Error Loading a Hub Model (Multilingual-MiniLM)
## Code Snippet

```
from transformers import AutoTokenizer, AutoModel
tokenizer = AutoTokenizer.from_pretrained("microsoft/Multilingual-MiniLM-L12-H384")
model = AutoModel.from_pretrained("microsoft/Multilingual-MiniLM-L12-H384")
```

- `transformers` version: 4.1.1, 3.1.0 (error in both)

## Error

```
TypeError: stat: path should be string, bytes, os.PathLike or integer, not NoneType
```

## Expected behavior

The [model and tokenizer](https://huggingface.co/microsoft/Multilingual-MiniLM-L12-H384) loads correctly. The error could be reproduced in a [colab notebook](https://colab.research.google.com/drive/1uFnBN-WdpK4PiamvdyizMCzJsrBtewKx?usp=sharing) .
Please note: This checkpoint uses BertModel with XLMRobertaTokenizer so AutoTokenizer won't work with this checkpoint!