missing from r61016


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@61018 954f8c5b-7b00-dc11-b283-0030488c597c
cancelling an operator popup now calls the operators cancel callback.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@61019 954f8c5b-7b00-dc11-b283-0030488c597c