Almost backout afcd46716d6a which breaks _select_best raising an ambiguity exception in debug mode. The problem is, before afcd4, *tests* ran in debug mode and we want this (e.g. we want to show, rather than swallow, select ambigüities). We juste replace the bogus __init__(vreg.config) by __init__(True), which is practically equivalent and also much more clear.

--- a/cwvreg.py	Wed Sep 17 13:43:31 2014 +0200
+++ b/cwvreg.py	Tue Jul 29 14:40:29 2014 +0200
@@ -241,7 +241,7 @@
 
 class CWRegistry(Registry):
     def __init__(self, vreg):
-        super(CWRegistry, self).__init__(vreg.config.debugmode)
+        super(CWRegistry, self).__init__(True)
         self.vreg = vreg
 
     @property