iotests: Set up Python logging

Set up Python logging module instead of relying on
QEMUMachine._debug to enable debugging messages.

Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Max Reitz <mreitz@redhat.com>
Cc: qemu-block@nongnu.org
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20170927130339.21444-3-ehabkost@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Lukáš Doktor <ldoktor@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

tests/qemu-iotests/iotests.py

@@ -28,6 +28,7 @@
 import struct
 import json
 import signal
+import logging
 
 
 # This will not work if arguments contain spaces but is necessary if we
@@ -467,6 +468,8 @@ def main(supported_fmts=[], supported_oses=['linux']):
     else:
         output = StringIO.StringIO()
 
+    logging.basicConfig(level=(logging.DEBUG if debug else logging.WARN))
+
     class MyTestRunner(unittest.TextTestRunner):
         def __init__(self, stream=output, descriptions=True, verbosity=verbosity):
             unittest.TextTestRunner.__init__(self, stream, descriptions, verbosity)