py3: return bytes from util.removeauth()

util.hidepassword() also returns bytes and we should deal in bytes as much as
possible.

This makes test-logexchange.t pass on Python 3.5

Differential Revision: https://phab.mercurial-scm.org/D3127

mercurial/util.py

@@ -2864,7 +2864,7 b' def removeauth(u):'
     '''remove all authentication information from a url string'''
     u = url(u)
     u.user = u.passwd = None
-    return str(u)
+    return bytes(u)
 
 timecount = unitcountfn(
     (1, 1e3, _('%.0f s')),