hgweb: remove one-off routing for file?style=raw
Now that both functions are using the same API, we can unify how
the command is called and perform command-specific behavior in the
command itself instead of in the high-level router.
Differential Revision: https://phab.mercurial-scm.org/D2788
http://example.com/no/anchor, branches: (None, [])
http://example.com/an/anchor, branches: ('foo', [])
http://example.com/no/anchor/branches, branches: (None, ['foo'])
http://example.com/an/anchor/branches, branches: ('bar', ['foo'])
http://example.com/an/anchor/branches-None, branches: ('foo', [])
http://example.com/, branches: (None, [])
http://example.com/, branches: (None, [])
http://example.com/, branches: ('foo', [])