request #7634 Tracker cardwall drag'n'drop looses the drop value if transition invalid

Change-Id: I952a7964ac3e0b179949fe4f2a6c798d3b09e388
Merge commit 'refs/changes/53/3253/2' of ssh://gerrit.tuleap.net:29418/tuleap into stable

* ssh://gerrit.tuleap.net:29418/tuleap:
  request #7634 Tracker cardwall drag'n'drop looses the drop value if transition invalid
This is Tuleap 7.7.99.22

Change-Id: If2fad58d887c16d5318943a336bf0171ddbdb2e7