Select filters in exposed blocks don't use their default value

Problem/Motivation

When an exposed select filter is attached to a view it's default value can be set, and works as expected.
However if "Exposed form in block" is used this select filter will now default to - Any - rather than the desired default value.

This isn't noticed for attached filters because although the default value is still set to - Any -, but then overridden by field handlers which set $form_state['input'].

For block filters this becomes an issue because it uses a cached $form, so the field handlers don't run.

Proposed resolution

Either:

1) Run field handlers on cached forms.

Or:

2) Set the default value correctly for select fields.

I suggest that (1) is less desired as it negates a lot of the point in using a cache, so arguably (2) is the way to go.

This is what (2) might look like:

views_handler_filter.inc

  ...
  public function exposed_translate(&$form, $type) {
    ...
    if ($type == 'value' && empty($this->always_required) && empty($this->options['expose']['required']) && $form['#type'] == 'select' && empty($form['#multiple'])) {
      $any_label = variable_get('views_exposed_filter_any_label', 'new_any') == 'old_any' ? t('<Any>') : t('- Any -');
      $form['#options'] = array('All' => $any_label) + $form['#options'];
-     $form['#default_value'] = 'All';
+     if (empty($form['#default_value'])) {
+       $form['#default_value'] = 'All';
+     }
    }
    ...
  }
  ...

Setting as needs work so someone can try rolling the above into a patch.