The streaming-test.log should be kept separate from spark-tests.log. Otherwise the streaming tests overwrite the spark tests logs as log4j is configured to not append. In fact, right now, the bagel and repl tests overwrite the logs of the core tests. I think we should keep it as "not append" (because it would be confusing to have older logs mixed with new logs) and have separate log files for core, streaming, bagel, repl (so that they dont overwrite each other).