Recurring WebApp Error: <type 'exceptions.KeyError'>: u'mins'

I'm getting loads of these, apparently mostly caused by googlebot. A quick inspection doesn't show any ``mins`` key in the code, so not sure what is going on.

Full traceback: https://gist.github.com/amercader/5575150

```
File '/usr/lib/ckan/beta/src/ckan/ckan/templates/page.html', line 65 in block "main_content"
  {% block primary %}
File '/usr/lib/ckan/beta/src/ckan/ckan/templates/page.html', line 78 in block "primary"
  {% block primary_content %}{% endblock %}
File '/usr/lib/ckan/beta/src/ckan/ckan/templates/package/resource_read.html', line 70 in block "primary_content"
  {% block resource_additional_information %}
File '/usr/lib/ckan/beta/src/ckan/ckan/templates/package/resource_read.html', line 99 in block "resource_additional_information"
  {% for key, value in h.format_resource_items(res.items()) %}
File '/usr/lib/ckan/beta/src/ckan/ckan/lib/helpers.py', line 1459 in format_resource_items
  value = formatters.localised_nice_date(datetime_)
File '/usr/lib/ckan/beta/src/ckan/ckan/lib/formatters.py', line 91 in localised_nice_date
  days).format(days=days)
KeyError: u'mins'
```