py3: use bytes() instead of str() on util.url()

We internally deal with bytes and anything as string breaks things.

Differential Revision: https://phab.mercurial-scm.org/D3285

mercurial/subrepoutil.py

@@ -106,7 +106,7 b' def state(ctx, ui):'
                 parent = util.url(parent)
                 parent.path = posixpath.join(parent.path or '', src)
                 parent.path = posixpath.normpath(parent.path)
-                joined = str(parent)
+                joined = bytes(parent)
                 # Remap the full joined path and use it if it changes,
                 # else remap the original source.
                 remapped = remap(joined)