Fix KeyError which occurs when not-existing entry is tried to be removed. Fixes #11109

lib/ansible/playbook/task.py

@@ -189,9 +189,9 @@ class Task(object):
 
             if 'su' in ds:
                 self.become=ds['su']
+                del ds['su']
             else:
                 self.become=True
-                del ds['su']
             if 'su_user' in ds:
                 self.become_user = ds['su_user']
                 del ds['su_user']