Fix: missing sequencer update

This should be fixed differently in the future. Read D3821 for more details.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D3821

source/blender/makesrna/intern/rna_sequencer.c

@@ -125,6 +125,7 @@ static void rna_Sequence_update(Main *UNUSED(bmain), Scene *UNUSED(scene), Point
 		Sequence *seq = (Sequence *) ptr->data;
 
 		BKE_sequence_invalidate_cache(scene, seq);
+		WM_main_add_notifier(NC_SCENE | ND_SEQUENCER, scene);
 	}
 }