HEAT - Validation of a template does not display the correct error message

If the heat template from a file source does not have the right syntax, the error displayed in horizon is
"An unknown problem occurred validating the template."

Heat engine is returning an error with an error message but that message is not propagated to the end user.
This is what I see in the horizon logs

HTTP/1.1 400 Bad Request
date: Wed, 18 Dec 2013 18:55:45 GMT
content-length: 769
content-type: application/json; charset=UTF-8

{"explanation": "At least one Resources member must be defined.", "code": 400, "error": {"message": "At least one Resources member must be defined.", "traceback": " File \"/usr/lib/python2.6/site-packages/heat/common/wsgi.py\", line 661, in __call__\n request, **action_args)\n File \"/usr/lib/python2.6/site-packages/heat/common/wsgi.py\", line 729, in dispatch\n return method(*args, **kwargs)\n File \"/usr/lib/python2.6/site-packages/heat/api/openstack/v1/util.py\", line 30, in handle_stack_method\n return handler(controller, req, **kwargs)\n File \"/usr/lib/python2.6/site-packages/heat/api/openstack/v1/stacks.py\", line 317, in validate_template\n raise exc.HTTPBadRequest(result['Error'])\n", "type": "HTTPBadRequest"}, "title": "Bad Request"}

2013-12-18 18:55:45,328 4601 ERROR openstack_dashboard.dashboards.project.stacks.forms <django.utils.functional.__proxy__ object at 0x7fdf0c4dab50>
Traceback (most recent call last):
  File "/usr/share/openstack-dashboard/openstack_dashboard/wsgi/../../openstack_dashboard/dashboards/project/stacks/forms.py", line 139, in clean
    validated = api.heat.template_validate(self.request, **kwargs)
  File "/usr/share/openstack-dashboard/openstack_dashboard/wsgi/../../openstack_dashboard/api/heat.py", line 88, in template_validate
    return heatclient(request).stacks.validate(**kwargs)
  File "/usr/lib/python2.6/site-packages/heatclient/v1/stacks.py", line 147, in validate
    resp, body = self.api.json_request('POST', '/validate', body=kwargs)
  File "/usr/lib/python2.6/site-packages/heatclient/common/http.py", line 210, in json_request
    resp, body_str = self._http_request(url, method, **kwargs)
  File "/usr/lib/python2.6/site-packages/heatclient/common/http.py", line 175, in _http_request
    raise exc.from_response(resp, body_str)
HTTPBadRequest: ERROR: At least one Resources member must be defined.

In this case horizon should display some message like "ERROR: At least one Resources member must be defined"