jquery/jquery — pull request #771 by MoonScript (2012-05-09 22:38:17+00:00)
Title: Strip out _submit_attached="true". Fixes #11649.

Under the following circumstances, a form tag retrieved via .html() will contain a jQuery-introduced attribute: _submit_attached="true".

1) When jQuery.support.submitBubbles is false (IE < 9)
2) When a submit event-handler is bound to the form via event delegation.
3) When that form has a submit event attempted.

You can see the bug here:
http://jsfiddle.net/MoonScript/adAaU/

Click the 1st button to see that the submit event was captured via jQuery. Click the 2nd button to see the HTML, which includes the _submit_attached="true" attribute that was not in the original source HTML. Then click the 3rd button to use that retrieved HTML to insert a new form into the DOM. When you click that new form's submit button, you'll see that the submit event is NOT captured by jQuery, because it contained the _submit_attached="true" attribute, so jQuery ignored it during its submit delegation process.

The fixed/expected result is illustrated here:
http://jsfiddle.net/MoonScript/adAaU/2/