title: result from "gsutil cp" is always in stderr, not stdout
body: <p>As the title, the results from "gsutil cp" doesn't redirect to stdout, it always redirect to stderr.</p>
  
  <p>As an example : <code>gsutil cp existed_file.txt . &gt; &gt;(tee -a out.log) 2&gt; &gt;(tee -a error.log &gt;&amp;2)</code> .
  In above command, out.log is empty, and error.log has a successful copy result.</p>
  
  <p>Its behavior is wrong, because if above command is correct, its output should return in out.log, not in error.log.</p>
  
  <p>How can i fix it ? </p>