Unexpected output from bart-large
I am looking this thread about generation, https://stackoverflow.com/questions/64904840/why-we-need-a-decoder-start-token-id-during-generation-in-huggingface-bart

I re-run his code,
Use ```facebook/bart-base``` model,
 ```
from transformers import *

import torch
model = BartForConditionalGeneration.from_pretrained('facebook/bart-base')
tokenizer = BartTokenizer.from_pretrained('facebook/bart-base')
input_ids = torch.LongTensor([[0, 894, 213, 7, 334, 479, 2]])
res = model.generate(input_ids, num_beams=1, max_length=100)

print(res)

preds = [tokenizer.decode(g, skip_special_tokens=True, clean_up_tokenization_spaces=True).strip() for g in res]
print(preds)
```
I get output:
```
tensor([[  2,   0, 894, 213,   7, 334, 479,   2]])
['He go to school.']
```
Then I just simply change the model to ```facebook/bart-large```  with everything kept the same, i.e.
 ```
from transformers import *

import torch
model = BartForConditionalGeneration.from_pretrained('facebook/bart-large')
tokenizer = BartTokenizer.from_pretrained('facebook/bart-large')
input_ids = torch.LongTensor([[0, 894, 213, 7, 334, 479, 2]])
res = model.generate(input_ids, num_beams=1, max_length=100)

print(res)

preds = [tokenizer.decode(g, skip_special_tokens=True, clean_up_tokenization_spaces=True).strip() for g in res]
print(preds)
```
Then I get output:
```
tensor([[  2, 894, 894, 213,   7, 334, 479,   2]])
['HeHe go to school.']
```
Is this normal?
Thanks.

@jc-hou: I just tested the above script and I get the same output as you. Why did you close the issue?<|||||>`res = model.generate(input_ids, num_beams=1, max_length=100, forced_bos_token_id=0)` solves the issue