a question about 'Interrupt execution on any error'

hi all,

according to the section entitled 'Interrupt execution on any error’ in the below URL:
http://docs.ansible.com/ansible/playbooks_delegation.html#rolling-update-batch-size

I wrote the below playbook:

in the documentation, it says the below content:

"second stage can’t be played if any server failed on “stage 1”

but what I got is not what the document says.