request #7676: Fatal Error on drag'n'drop on old planning view

Change-Id: I2f52e17bfedd029acfb89eed83ddf40a7890eb83
Merge commit 'refs/changes/42/3342/1' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  request #7676: Fatal Error on drag'n'drop on old planning view

Change-Id: I2e3363ec8a6dc96016be9863d9f754c6045fc12b
This is Tuleap 7.7.99.73

Change-Id: I137fddb839541f13a585255107dd5f8ff6f7200d