Issue 1407902: urlparse does not know about sftp: urls

>>> from urlparse import urlparse
>>> urlparse('sftp://example.com//absolute/path')
('sftp', '', '//example.com//absolute/path', '', '', '')
>>> urlparse('sftp://example.com/relative/path')
('sftp', '', '//example.com/relative/path', '', '', '')

netloc should be populated in both cases