hgweb: rewrite two X or Y and Z ad-hoc ternaries with Y if X else Z
Just easier to muddle through for my brain now that I don't see the
old pattern much anymore.
Differential Revision: https://phab.mercurial-scm.org/D1077
httppeer: use native strings for headers
On Python 3, we need to use unicodes, rather than bytes. This lets
test-pull.t get a lot further along.
Differential Revision: https://phab.mercurial-scm.org/D887