title: Python2.7 log level of logging doesn't work
body: <p>It seems recently there were some changes of python logging package. Some code work previously doesn't work now. And I am confused. My python version is Python 2.7.15.</p>
  
  <p>The first example I don't understand is that below only prints "WARNING:root:hello from warn". If I understand correctly, "logging.info" actually calls the root logger, and root logger default to warn level. So the first "hello from info" is ignored, which is fine. But why the second "hello from info" is also not printed? </p>
  
  <pre><code>import logging 
  logging.info("hello from info")
  logging.warn("hello from warn")
  
  logging.basicConfig(level=logging.INFO)
  logging.info("hello from info")
  </code></pre>
  
  <p>The second question is the logging level of Handler versus logger. If we set the log level for both the handler and logger, which one is working? Or what if we just set level for Handler? Take the example as below. We already set the log level for StreamHandler, <em>but the "hello from info" is not printed to stdout</em>. Only the "hello from warn" (Besides, it is not "WARNING:t:hello from warn"). Why is that? </p>
  
  <pre><code>import logging
  ch = logging.StreamHandler()
  ch.setLevel(logging.INFO)
  logger = logging.getLogger('t')
  logger.addHandler(ch)
  logger.info("hello from info")
  logger.warn("hello from warn")
  </code></pre>