Oh, I think I remember discussing the filename thing before, and we concluded that there didn't need to be a python API, and we were expected to redirect the output as appropriate.
I thought about clobbering sys.stdout, but I think the output isn't coming from python, so we would need to intercept it at an even higher level. That means putting something in BatchCmdLineTask.batchCommand, but I'm not sure how to do that in a good way when multiple processes are running that one command.
Maybe we should just remove the log file altogether, and rely on the batch system catching the stdout? Then we need to make sure that the host and PID are being prepended to the log messages.