Clarifies how Ansible processes multiple failed_when conditions (an…

…sible#55941)

Docs: Clarify that multiple failed_when conditions join with AND not OR to counter third-party pages online incorrectly stating that it uses `OR`. ([example](https://groups.google.com/d/msg/ansible-project/cIaQTmY3ZLE/c5w8rlmdHWIJ)).

docs/docsite/rst/user_guide/playbooks_error_handling.rst

@@ -63,11 +63,9 @@ the handler from running, such as a host becoming unreachable.)
 Controlling What Defines Failure
 ````````````````````````````````
 
-Suppose the error code of a command is meaningless and to tell if there
-is a failure what really matters is the output of the command, for instance
-if the string "FAILED" is in the output.
+Ansible lets you define what "failure" means in each task using the ``failed_when`` conditional. As with all conditionals in Ansible, lists of multiple ``failed_when`` conditions are joined with an implicit ``and``, meaning the task only fails when *all* conditions are met. If you want to trigger a failure when any of the conditions is met, you must define the conditions in a string with an explicit ``or`` operator.
 
-Ansible provides a way to specify this behavior as follows::
+You may check for failure by searching for a word or phrase in the output of a command::
 
     - name: Fail task when the command error output prints FAILED
       command: /usr/bin/example-command -x -y -z
@@ -93,14 +91,18 @@ In previous version of Ansible, this can still be accomplished as follows::
         msg: "the command failed"
       when: "'FAILED' in command_result.stderr"
 
-You can also combine multiple conditions to specify this behavior as follows::
+You can also combine multiple conditions for failure. This task will fail if both conditions are true::
 
     - name: Check if a file exists in temp and fail task if it does
       command: ls /tmp/this_should_not_be_here
       register: result
       failed_when:
-        - '"No such" not in result.stdout'
         - result.rc == 0
+        - '"No such" not in result.stdout'
+
+ If you want the task to fail when only one condition is satisfied, change the ``failed_when`` definition to::
+
+      failed_when: result.rc == 0 or "No such" not in result.stdout
 
 .. _override_the_changed_result:
 
@@ -168,7 +170,7 @@ Blocks only deal with 'failed' status of a task. A bad task definition or an unr
         - debug:
             msg: 'I caught an error, can do stuff here to fix it, :-)'
 
-This will 'revert' the failed status of the outer ``block`` task for the run and the play will continue as if it had succeeded. 
+This will 'revert' the failed status of the outer ``block`` task for the run and the play will continue as if it had succeeded.
 See :ref:`block_error_handling` for more examples.
 
 .. seealso::
@@ -185,5 +187,3 @@ See :ref:`block_error_handling` for more examples.
        Have a question?  Stop by the google group!
    `irc.freenode.net <http://irc.freenode.net>`_
        #ansible IRC chat channel
-
-