possible NoneType error

[Christopher Trudeau]

I've used ConcurrentLogHandler as a basis for a handler I've written (thanks, way easier than starting from scratch). In the process of going through unittests I was able to trigger a situation where the stream is not locked and the check for the closed attribute causes a NoneType error. It is a one line fix:

    def close(self):
        """
        Close log stream and stream_lock. """
        try:
            self._close()
            if hasattr(self.stream_lock, 'closed') and \
                    not self.stream_lock.closed:
                self.stream_lock.close()
        finally:
            self.stream_lock = None
            Handler.close(self)

Just add the "hasattr". I don't think it was something I modified that caused the problem to arise so I figured I'd pass along the fix just in case. If it was my stupidity that triggered the situation feel free to ignore the ticket :)