Use ==/!= to compare str, bytes, and int literals

Identity is not the same thing as equality in Python.

$ __[flake8](http://flake8.pycqa.org)  . --count --select=E9,F63,F7,F82 --show-source --statistics__
```
    if resp.status_code is 200:
       ^
1     F632 use ==/!= to compare str, bytes, and int literals
1
```