configitems: register the 'ui.interface.chunkselector' config

mercurial/configitems.py

@@ -632,6 +632,9 b" coreconfigitem('ui', 'interactive',"
 coreconfigitem('ui', 'interface',
     default=None,
 )
+coreconfigitem('ui', 'interface.chunkselector',
+    default=None,
+)
 coreconfigitem('ui', 'logblockedtimes',
     default=False,
 )

mercurial/ui.py

@@ -1149,7 +1149,7 b' class ui(object):'
             defaultinterface = i
 
         choseninterface = defaultinterface
-        f = self.config("ui", "interface.%s" % feature, None)
+        f = self.config("ui", "interface.%s" % feature)
         if f in availableinterfaces:
             choseninterface = f