Contextual filter breaks view when no default value in url

Since views-3.1, I have the following problem.

When I try to edit the contextual filter in the admin overlay, I get the following:

Er is een AJAX HTTP fout opgetreden.
HTTP-resultaatcode: 200
Debug informatie volgt.
Pad: http://XXXXXXXXXXXXX.nl/admin/structure/views/ajax/config-item/mededelingen_van_mijn_post/page_1/argument/field_afdeling_tid
Statustekst: OK
Antwoordtekst: Notice: Undefined index:  style_options in options_validate() (line 222 of /home/adrupal/www/sites/all/modules/views/plugins/views_plugin_style.inc). =>

I did some research and found out that options_validate in views_plugin_style.inc is new since views-3.0. views_plugin_style_summary extends views_plugin_style, but completely overrides options_form and the result doesn't include the 'grouping' option. However, views_plugin_style_summary doesn't override options_validate in views_plugin_style. This function checks the input for the grouping option. As a result, it is called when submitting the summary form, a non-existing form_state entry is checked, an error occurs and you can't save the contextual filter form.

The solution is very simple: add an empty options_validate function to views_plugin_style_summary. This will cause the original to not be called and the summary will work again.

Please fix quickly!