Show nicer error message when there is a ticket with multiple parents
|Reported by:||rjollos||Owned by:||ChrisNelson|
Here is the error I saw when I tried to include a ticket in a milestone displayed in the TracJsGanttChart and that ticket had multiple parents (via SubticketsPlugin).
It might not be immediately obvious why this error is occurring, and that you can't have any tickets with multiple parents, so I propose to display a more user friendly error for this condition.
I can provide a patch this weekend.