AttributeError: 'list' object has no attribute 'clone' with BartTokenizer
## Environment info
<!-- You can run the command `transformers-cli env` and copy-and-paste its output below.
     Don't forget to fill out the missing fields in that output! -->
     
- `transformers` version: 3.1.0 
- Platform: MacOS
- Python version: 3.7.6
- PyTorch version (GPU?): 1.6.0 (No GPU)
- Tensorflow version (GPU?): 2.3.0 (No GPU)
- Using GPU in script?: No
- Using distributed or parallel set-up in script?: No

### Who can help
- Summarization & Bart: @sshleifer

## Information

- Model I am using (Bert, XLNet ...): **`BartTokenizer, BartForConditionalGeneration`**
- I'm loading the model from the directory. I saved the model which I initially loaded with `'facebook/bart-large-cnn'` and saved later after using `.save_pretrained(tmp_model_dir)` command.

The problem arises when using:
* [x] example scripts: (give details below)

The tasks I am working on is:
* [x] summarization task: (give the name)

## To reproduce

Steps to reproduce the behavior:

```python
from transformers import BartTokenizer, BartForConditionalGeneration

model = BartTokenizer.from_pretrained('/Downloads/facebook-bart-large-cnn')
tokenizer = BartForConditionalGeneration.from_pretrained('/Downloads/facebook-bart-large-cnn')

raw_text = """ New York (CNN)When Liana Barrientos was 23 years old, she got married in Westchester County, New York.
A year later, she got married again in Westchester County, but to a different man and without divorcing her first husband.
Only 18 days after that marriage, she got hitched yet again. Then, Barrientos declared "I do" five more times, sometimes only within two weeks of each other.
In 2010, she married once more, this time in the Bronx. In an application for a marriage license, she stated it was her "first and only" marriage.
Barrientos, now 39, is facing two criminal counts of "offering a false instrument for filing in the first degree," referring to her false statements on the
2010 marriage license application, according to court documents.
Prosecutors said the marriages were part of an immigration scam.
On Friday, she pleaded not guilty at State Supreme Court in the Bronx, according to her attorney, Christopher Wright, who declined to comment further.
After leaving court, Barrientos was arrested and charged with theft of service and criminal trespass for allegedly sneaking into the New York subway through an emergency exit, said Detective
Annette Markowski, a police spokeswoman. In total, Barrientos has been married 10 times, with nine of her marriages occurring between 1999 and 2002.
All occurred either in Westchester County, Long Island, New Jersey or the Bronx. She is believed to still be married to four men, and at one time, she was married to eight men at once, prosecutors say.
Prosecutors said the immigration scam involved some of her husbands, who filed for permanent residence status shortly after the marriages.
Any divorces happened only after such filings were approved. It was unclear whether any of the men will be prosecuted.
The case was referred to the Bronx District Attorney\'s Office by Immigration and Customs Enforcement and the Department of Homeland Security\'s
Investigation Division. Seven of the men are from so-called "red-flagged" countries, including Egypt, Turkey, Georgia, Pakistan and Mali.
Her eighth husband, Rashid Rajput, was deported in 2006 to his native Pakistan after an investigation by the Joint Terrorism Task Force.
If convicted, Barrientos faces up to four years in prison.  Her next court appearance is scheduled for May 18.
"""

inputs = tokenizer([raw_text], max_length=1024, return_tensors='pt', truncation=True)
```

- Error:
```python
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-4-74e209dd3da0> in <module>
----> 1 inputs = tokenizer([raw_text], max_length=1024, return_tensors='pt', truncation=True)

~/anaconda3/lib/python3.7/site-packages/torch/nn/modules/module.py in _call_impl(self, *input, **kwargs)
    720             result = self._slow_forward(*input, **kwargs)
    721         else:
--> 722             result = self.forward(*input, **kwargs)
    723         for hook in itertools.chain(
    724                 _global_forward_hooks.values(),

~/anaconda3/lib/python3.7/site-packages/transformers/modeling_bart.py in forward(self, input_ids, attention_mask, encoder_outputs, decoder_input_ids, decoder_attention_mask, past_key_values, labels, use_cache, output_attentions, output_hidden_states, return_dict, **unused)
   1074             output_attentions=output_attentions,
   1075             output_hidden_states=output_hidden_states,
-> 1076             return_dict=return_dict,
   1077         )
   1078         lm_logits = F.linear(outputs[0], self.model.shared.weight, bias=self.final_logits_bias)

~/anaconda3/lib/python3.7/site-packages/torch/nn/modules/module.py in _call_impl(self, *input, **kwargs)
    720             result = self._slow_forward(*input, **kwargs)
    721         else:
--> 722             result = self.forward(*input, **kwargs)
    723         for hook in itertools.chain(
    724                 _global_forward_hooks.values(),

~/anaconda3/lib/python3.7/site-packages/transformers/modeling_bart.py in forward(self, input_ids, attention_mask, decoder_input_ids, encoder_outputs, decoder_attention_mask, past_key_values, use_cache, output_attentions, output_hidden_states, return_dict, **kwargs)
    904                 decoder_input_ids=decoder_input_ids,
    905                 decoder_padding_mask=decoder_attention_mask,
--> 906                 causal_mask_dtype=self.shared.weight.dtype,
    907             )
    908         else:

~/anaconda3/lib/python3.7/site-packages/transformers/modeling_bart.py in _prepare_bart_decoder_inputs(config, input_ids, decoder_input_ids, decoder_padding_mask, causal_mask_dtype)
    146     pad_token_id = config.pad_token_id
    147     if decoder_input_ids is None:
--> 148         decoder_input_ids = shift_tokens_right(input_ids, pad_token_id)
    149     bsz, tgt_len = decoder_input_ids.size()
    150     if decoder_padding_mask is None:

~/anaconda3/lib/python3.7/site-packages/transformers/modeling_bart.py in shift_tokens_right(input_ids, pad_token_id)
    204 def shift_tokens_right(input_ids, pad_token_id):
    205     """Shift input ids one token to the right, and wrap the last non pad token (usually <eos>)."""
--> 206     prev_output_tokens = input_ids.clone()
    207     index_of_eos = (input_ids.ne(pad_token_id).sum(dim=1) - 1).unsqueeze(-1)
    208     prev_output_tokens[:, 0] = input_ids.gather(1, index_of_eos).squeeze()

AttributeError: 'list' object has no attribute 'clone'
```

I think you flipped model and tokenizer at the beginning. It should be
```python

from transformers import BartTokenizer, BartForConditionalGeneration

tokenizer = BartTokenizer.from_pretrained('/Downloads/facebook-bart-large-cnn')
model = BartForConditionalGeneration.from_pretrained('/Downloads/facebook-bart-large-cnn')

```<|||||>Pls reopen if there is another issue!<|||||>Damn, this was embarrassing bug on my end. Thank you! 🍻