Calendar Prev/Next buttons linking to wrong dates
drush dl date --select 
Choose one of the available releases for date:
 [0]  :  Cancel                                                
 [1]  :  7.x-2.x-dev  -  2015-Jun-16  -  Development           
 [2]  :  7.x-2.9-rc1  -  2015-Mar-27  -  Supported             
 [3]  :  7.x-2.8      -  2014-Jul-29  -  Recommended, Security 
 [4]  :  7.x-1.x-dev  -  2013-Sep-30  -  Development    


So if I have 7.x-2.8 - It's okay.   7.x-2.9-rc1 or  7.x-2.x-dev  both jump ahead by two months.drush dl date --select 

Of the ones available, dev and rc1 have an issue with the next button. 2.8 is fine but it defaults the calendar name to include the first day of the month. So you must choose between a bad title format or a bad next button.

My solution: I moved back to Date 7.x-2.8 and then overrode date-views-pager.tpl.php in my theme with the following:

&lt;div class="date-nav-wrapper clearfix&lt;?php if (!empty($extra_classes)) print $extra_classes; ?&gt;"&gt;
  &lt;div class="date-nav item-list"&gt;
    &lt;div class="date-heading"&gt;
      &lt;h3&gt;&lt;?php
        print date("F", strtotime($nav_title))
            . ' '
            . date("Y", strtotime($nav_title));
        ?&gt;
      &lt;/h3&gt;