Fixed swift-bench when using -b and a conf file

Change-Id: I72448cd8578b53a658f151354a26066772e4b9ec

bin/swift-bench

@@ -127,6 +127,7 @@ if __name__ == '__main__':
             sys.exit("No such conf file: %s" % conf)
         conf = readconf(conf, 'bench', log_name='swift-bench',
                         defaults=CONF_DEFAULTS)
+        conf['bench_clients'] = []
     else:
         conf = CONF_DEFAULTS
     parser.set_defaults(**conf)

swift/common/bench.py

@@ -116,7 +116,7 @@ class BenchServer(object):
             level = logging.DEBUG if conf.log_level.lower() == 'debug' \
                 else logging.INFO
             logger.setLevel(level)
-            loghandler = logging.StreamHandler(stream=client_file)
+            loghandler = logging.StreamHandler(client_file)
             logformat = logging.Formatter(
                 '%(server)s %(asctime)s %(levelname)s %(message)s')
             loghandler.setFormatter(logformat)