exthelper: switch to using the registrar merging method

mercurial/exthelper.py

@@ -96,9 +96,9 b' class exthelper(object):'
         self._uipopulatecallables.extend(other._uipopulatecallables)
         self._extcallables.extend(other._extcallables)
         self._repocallables.extend(other._repocallables)
-        self.filesetpredicate._table.update(other.filesetpredicate._table)
-        self.revsetpredicate._table.update(other.revsetpredicate._table)
-        self.templatekeyword._table.update(other.templatekeyword._table)
+        self.filesetpredicate._merge(other.filesetpredicate)
+        self.revsetpredicate._merge(other.revsetpredicate)
+        self.templatekeyword._merge(other.templatekeyword)
         self._commandwrappers.extend(other._commandwrappers)
         self._extcommandwrappers.extend(other._extcommandwrappers)
         self._functionwrappers.extend(other._functionwrappers)