fix(task): only count unique tasks in a bucket when checking bucket limit

This fixes a bug where the current number of tasks in a bucket was computed wrong when moving tasks into a bucket with a limit. Sometimes the bug would prevent adding a task to a bucket which seemed to have space left but ultimately failed when moving the task.

pkg/models/tasks.go

@@ -640,6 +640,7 @@ func checkBucketLimit(s *xorm.Session, t *Task, bucket *Bucket) (err error) {
 	if bucket.Limit > 0 {
 		taskCount, err := s.
 			Where("bucket_id = ?", bucket.ID).
+			GroupBy("task_id").
 			Count(&TaskBucket{})
 		if err != nil {
 			return err