VTK Debug Leaks are triggered by most core tests, and if you look at the
"Falling/Passing Graph" it happened Nov 15 or 16 :
http://cdash.mitk.org/testDetails.php?test=12704110&build=657619
http://cdash.mitk.org/testDetails.php?test=12704026&build=657619
If it's not easy to find I could try to setup an automatic git bisect.