Empty env variable raises KeyError

[osantana]

I've created a .env file with:

FOO=

... and when I try to get FOO decouple raises a KeyError exception:

$ cat .env
FOO=
BAR=1

>>> from decouple import config
>>> config("BAR")
'1'
>>> config("BAZ", "undefined")
'undefined'
>>> config("FOO", "undefined")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "decouple.py", line 190, in __call__
    return self.config(*args, **kwargs)
  File "decouple.py", line 73, in __call__
    return self.get(*args, **kwargs)
  File "decouple.py", line 55, in get
    value = self.repository.get(option)
  File "decouple.py", line 123, in get
    return self.data.get(key) or os.environ[key]
  File "/home/osantana/.virtualenvs/opinious/lib/python2.7/UserDict.py", line 23, in __getitem__
    raise KeyError(key)
KeyError: 'FOO'