Totara 2.2.15 is a "snapshot" release containing bug fixes and minor improvements.
Here's the 2.2.15 changelog:
Release 2.2.15 (21st February 2013):
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Database upgrades:
T-10069 Update certificate module to latest version
T-8078 Fix Facetoface session timezones
Improvements:
T-9898 Make my home/learning consistent
T-10297 Add position start and end dates to totara_sync
T-10266 Remove minimum time required in Programs
Bug fixes:
T-5879 Fix references to moodle in auth.php
T-5879 Fix the fileupload text descriptions in kiwifruit theme
T-10288 Fix for front page favicon in kiwifruit theme
T-10254 Fix Filepicker to stop deletion of draft files
T-10030 Fix for dialog issues when closing and reopening them
T-10291 Fix for issue with "menu of choices" user custom profile fields
T-10148 Fix recurring courses to stop transfering course completion items
T-10296 Fix progress bar when course completed via rpl
T-10302 Fix course tooltip when using enrolment key on course with Self Enrolment enabled
T-10233 Fix extra div in course (Topics format) markup when summary is empty
T-10289 Fix MSSQL error for date custom field rules in Audiences
T-10304 Fix dates in Excel download for non-English languages
T-10294 Fix duplicate content being suppressed in mod/scorm/report
T-10122 Fix datepicker error when creating new Learning Plan
T-10251 Fix ability to remove mandatory courses from competencies in Learning Plans
T-10311 Fix ability to submit dialogs without selected values in Programs
T-10257 Fix sending of tasks/alerts on Facetoface signup when email to user fails
T-10133 Fix display of OS-specific file path in totara_sync
T-10229 Fix overwriting of required fields with empty values in totara_sync