I just did an upgrade from the calendar and date module of which calendar needed to move from 6.x-2.x-dev to 6.x-2.4 version which seemed a pitb exercise. I hope I missed some skills :-p

The following command was not working

drush upc calendar-6.x-2.4

So what I did was download the latest version offsite. Then diff the module trees.

cd /tmp
drush dl calendar-6.x-2.4
cd /my-site/sites/all/modules/calendar
cp -r /tmp/calendar/* ./