Add warn directive

byrd/config.py

@@ -134,6 +134,7 @@ class Task(Node):
         'send': Atom,
         'to': Atom,
         'assert': Atom,
+        'warn': Atom,
         'env': EnvNode,
         'multi': MultiList,
         'fmt': Atom,

byrd/main.py

@@ -317,6 +317,10 @@ def run_task(task, host, cli, env=None):
             logger.info('Assert ok')
         else:
             raise ByrdException('Assert "%s" failed!' % assert_)
+
+    if task.get('warn'):
+        msg = Env(env, res).fmt(task['warn'])
+        logger.warning(msg)
     return res