It doesn't make any difference in this case, because pidof gives a bad exit status when there is no result, but I don't think check_output can return None.

I created an empty directory and ran:
```
>>> subprocess.check_output(['ls'])
''
```

It'd probably work better to either check for empty string, or possibly even anything that resolves to false
```python
if subprocess.check_output(['pidof', 'rhsmcertd']):
    return True:
return False
```
This way if for some reason it gives us null, empty string, empty list etc, we're safe