markAsCanceled
Undo a writing block back to free (a write was cancelled). Mirrors mark_as_canceled. Only acts on a writing block; a no-op otherwise. If the piece becomes empty it is removed from the download list.
Undo a writing block back to free (a write was cancelled). Mirrors mark_as_canceled. Only acts on a writing block; a no-op otherwise. If the piece becomes empty it is removed from the download list.