using ConfigParser.read_file for PY3

cli/koji_cli/commands.py

@@ -5823,10 +5823,7 @@ def handle_image_build(options, session, args):
         if not os.path.exists(task_options.config):
             parser.error(_("%s not found!" % task_options.config))
         section = 'image-build'
-        config = six.moves.configparser.ConfigParser()
-        conf_fd = open(task_options.config)
-        config.readfp(conf_fd)
-        conf_fd.close()
+        config = koji.read_config_files(task_options.config)
         if not config.has_section(section):
             parser.error(_("single section called [%s] is required" % section))
         # pluck out the positional arguments first