Inline-if inside button triggers deprecation warning and error

I'm trying to bind whether a button is active or disabled on a computed property but get this depcreation warning and error afterwards.

This is troublesome button (Ember 1.11.1 here):

<button {{ action 'loadMore' }} {{if canLoadMore 'active' 'disabled'}}>Load More Posts...</button>

This warnining and error:

DEPRECATION: Returning a string of attributes from a helper inside an element is deprecated.
Uncaught TypeError: Cannot read property 'replace' of undefined

on this function:

if (value) {
  Ember['default'].deprecate('Returning a string of attributes from a helper inside an element is deprecated.');

  var parts = value.toString().split(/\s+/);
  for (var i = 0, l = parts.length; i < l; i++) {
    var attrParts = parts[i].split('=');
    var attrName = attrParts[0];
    var attrValue = attrParts[1];

    attrValue = attrValue.replace(/^['"]/, '').replace(/['"]$/, '');

    env.dom.setAttribute(domElement, attrName, attrValue);
  }