Fix roundup-server logging for Python 3. Using the roundup-server support for redirecting output to a log file fails with Python 3: sys.stdout = sys.stderr = open(self["LOGFILE"], 'a', 0) ValueError: can't have unbuffered text I/O Thus, this patch switches that redirection to use line-buffered output (1 as third argument to open), which works with both Python 2 and Python 3.