'__console__' instead of '__main__' as __name__ in bpython 0.20.1

this works:
```
(py3) DC@bdd14:~/code/stable$ bpython
bpython version 0.20.1 on top of Python 3.8.5 /home/.../miniconda3/envs/py3/bin/python
>>> __name__
'__main__'
```

but this doesn't:
```
(py3) DC@bdd14:~/code/stable$ bpython -i main.py
bpython version 0.20.1 on top of Python 3.8.5 /home/.../miniconda3/envs/py3/bin/python
>>> __name__
'__console__'
```