Also make sure remote_user is defaulted correctly for delegated hosts

Fixes #13323

lib/ansible/playbook/play_context.py

@@ -334,6 +334,8 @@ class PlayContext(Base):
                 display.debug("no remote address found for delegated host %s\nusing its name, so success depends on DNS resolution" % delegated_host_name)
                 delegated_vars['ansible_host'] = delegated_host_name
 
+            # reset the port back to the default if none was specified, to prevent
+            # the delegated host from inheriting the original host's setting
             for port_var in MAGIC_VARIABLE_MAPPING.get('port'):
                 if port_var in delegated_vars:
                     break
@@ -342,6 +344,13 @@ class PlayContext(Base):
                     delegated_vars['ansible_port'] = 5986
                 else:
                     delegated_vars['ansible_port'] = C.DEFAULT_REMOTE_PORT
+
+            # and likewise for the remote user
+            for user_var in MAGIC_VARIABLE_MAPPING.get('remote_user'):
+                if user_var in delegated_vars:
+                    break
+            else:
+                delegated_vars['ansible_user'] = None
         else:
             delegated_vars = dict()
 

test/units/playbook/test_play_context.py

@@ -91,6 +91,7 @@ class TestPlayContext(unittest.TestCase):
         mock_task.become_user   = 'mocktaskroot'
         mock_task.become_pass   = 'mocktaskpass'
         mock_task._local_action = False
+        mock_task.delegate_to   = None
 
         all_vars = dict(
             ansible_connection = 'mock_inventory',