exchange: make narrow ACL presence imply narrow=True

exchange: make narrow ACL presence imply narrow=True

And refactor the logic for determining when to invoke our custom
changegroup part function so it is only conditional on
narrow being set. This makes it more obvious under which
conditions we should invoke the custom implementation.

Also use raw strings so **kwargs works on Python 3.

Differential Revision: https://phab.mercurial-scm.org/D4013

--- a/hgext/narrow/narrowbundle2.py	Sat Jul 28 14:52:46 2018 -0700
+++ b/hgext/narrow/narrowbundle2.py	Sat Jul 28 17:33:20 2018 -0700
@@ -309,9 +309,9 @@
     def wrappedcgfn(*args, **kwargs):
         repo = args[1]
         if repo.ui.has_section(_NARROWACL_SECTION):
-            getbundlechangegrouppart_narrow(
-                *args, **exchange.applynarrowacl(repo, kwargs))
-        elif kwargs.get(r'narrow', False):
+            kwargs = exchange.applynarrowacl(repo, kwargs)
+
+        if kwargs.get(r'narrow', False):
             getbundlechangegrouppart_narrow(*args, **kwargs)
         else:
             origcgfn(*args, **kwargs)

--- a/mercurial/exchange.py	Sat Jul 28 14:52:46 2018 -0700
+++ b/mercurial/exchange.py	Sat Jul 28 17:33:20 2018 -0700
@@ -1872,9 +1872,11 @@
 
     new_args = {}
     new_args.update(kwargs)
-    new_args['includepats'] = req_includes
+    new_args[r'narrow'] = True
+    new_args[r'includepats'] = req_includes
     if req_excludes:
-        new_args['excludepats'] = req_excludes
+        new_args[r'excludepats'] = req_excludes
+
     return new_args
 
 def _computeellipsis(repo, common, heads, known, match, depth=None):