Fix #905

[slozier]

Update socket.getfqdn to properly handle empty string and 0.0.0.0

[simplicbe]

As an additional hint, you maybe could assert host for null and give a specific error message. Else it will crash on .Trim() with a very unlucky NullReferenceException.

[slozier]

I was just going by what cpython does (fails by calling .strip on None), but I guess there's no reason we can't throw a TypeError instead.

[slide]

Does this follow the CPython way?

[slozier]

CPython deals with the name argument in the exact same way (see Lib\socket.py):

    name = name.strip()
    if not name or name == '0.0.0.0':
        name = gethostname()