Subject of the issue

If form contains (as child node) input field with form attribute pointed to another form an error is thrown when you interact with input field (focus, input etc).

Your environment

• jQuery Validation Plugin v1.16.0
• Chrome Version 59.0.3071.115

Steps to reproduce

See the simple example: https://jsfiddle.net/hc06nmtj/1/
Click on second input and check console logs

Expected behaviour

Ignore such fields, since they are not belong to validated form

Actual behaviour

Error is thrown