Granularity without timezone conversion and views filter problem (No results)

Please, add this line in date/date_api/date_api.sql.inc, in function sql_tz(), below line 275:

<?php

if (empty($this->local_timezone_field) && (empty($this->local_timezone))) $localzone = $db_zone;

?>

Here comes the reason why and my way to it:

• I added a date field with granularity (Y/m) and had to set timezone conversion to none, as this is required for such a granularity.
• Then I added an exposed filter to my view - which gave no results.
• I found the solution here for translatable fields: http://drupal.org/node/1057544#comment-4379906 but my filter still didn't work
• Devel module showed me, that the query sent to the database contained: (DATE_FORMAT(CONVERT_TZ(STR_TO_DATE(field_data_field_asgb.field_asgb_value, '%Y-%m-%dT%T'), 'UTC', ''), '%Y-%m'). The result is NULL as CONVERT_TZ needs the second Timezone argument.
• The above line solved the problem for me and should have no negative effect (sure, this has to be confirmed by others ...).

Thanks and greetings from Austria!