This looks like a nice library. So is python-requests. Every time I see this sort of libraries though, I can't help to wonder - why standard python libraries are so bad that people need to create these helpers.
They aren't "so bad", you can't expect the standard library to meet the requirements of everyone. Most of what this library achieves can be done with urlparse, it just has some additional "nice to haves". Also, see the comments about not using a MultiDict as a good indicator of why this problem isn't solved in the stdlib.
Much of the stdlib was written before niceties like keyword params and generators, others just don't have as nice a design as they could, hence the helpers.