url: more bytes/unicodes fussing in url.py around auth handling
Once again, these methods are a little annoying to handle because they
can get unicodes or bytes depending on who's calling. I think we can
probably clean this up a TON once we can run something like pytype and
do typechecking of our Python, but until then this is going to be the
easy way out. This fixes test-http-bundle1.t.
Differential Revision: https://phab.mercurial-scm.org/D2599