Fix possible IntegrityError when deleting task that is part of a contest - #1470

Fix possible IntegrityError when deleting task that is part of a contest#1470

prandla merged 2 commits into

cms-dev:maincms-dev/cms:mainfrom

e-i-o:bugfix-delete-taske-i-o/cms:bugfix-delete-taskCopy head branch name to clipboard