In addition to checking for scheme='http', we should also check that
netloc has a value. There are many meaningless URLs that pass the
current check. For instance:
In [5]: urlparse("http://")
Out[5]: ParseResult(scheme='http', netloc='', path='', params='',
query='', fragment='')
In [6]: urlparse("http:///")
Out[6]: ParseResult(scheme='http', netloc='', path='/', params='',
query='', fragment='')
In addition to checking for scheme='http', we should also check that netloc has a value. There are many meaningless URLs that pass the current check. For instance:
netloc should always have a value.