replace callable()

dist.py

@@ -545,7 +545,7 @@ Common commands: (see '--help-commands' for more)
             for (help_option, short, desc, func) in cmd_class.help_options:
                 if hasattr(opts, parser.get_attr_name(help_option)):
                     help_option_found=1
-                    if callable(func):
+                    if hasattr(func, '__call__'):
                         func()
                     else:
                         raise DistutilsClassError(