Empty (but present) authority component lost

[chrysn]

The library in its latest pip version (1.5.0; also observed in 1.4 as shipped in Debian) does not distinguish between present and absent authority components:

>>> rfc3986.urlparse('foo:///').unsplit()
'foo:/'

I don't see how RFC3986 would justify normalizing this away, especially given the comment on page41 that in some cases a URI would be normalized to one that has an empty (not absent) authority.