Rails3 disable_with remote form button immediately gets re-enabled

When submitting a remote form with a "disable_with" option, the reasonable expectation is that the button will be re-enabled after the ajax response. Instead, the button is immediately re-enabled after the request is made but before the response is received. The problem is that the re-enabling code in rails.js (lines 167-174) is fired on ajax:after:

  document.on("ajax:after", "form", function(event, element) {
    var inputs = element.select("input[type=submit][disabled=true][data-disable-with]");
    inputs.each(function(input) {
      input.value = input.readAttribute('data-original-value');
      input.removeAttribute('data-original-value');
      input.disabled = false;
    });
  });

If changed to be ajax:complete (line 167):

  document.on("ajax:complete", "form", function(event, element) { 
    //original code here
  }

The code works as expected: the button is disabled until the ajax response is received.