qmp.py: Avoid "has_key" usage

The "has_key" is deprecated in favor of "__in__" operator.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20170818142613.32394-9-ldoktor@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

scripts/qmp/qmp.py

@@ -197,7 +197,7 @@ def command(self, cmd, **kwds):
         Build and send a QMP command to the monitor, report errors if any
         """
         ret = self.cmd(cmd, kwds)
-        if ret.has_key('error'):
+        if "error" in ret:
             raise Exception(ret['error']['desc'])
         return ret['return']