COW Fix: Border selecting bones on rigs broke

Annoyingly, this was working as recently as yesterday...

source/blender/editors/space_view3d/view3d_select.c

@@ -2173,6 +2173,8 @@ static int do_object_pose_box_select(bContext *C, ViewContext *vc, rcti *rect, b
 						DEG_id_tag_update(&vc->obact->id, OB_RECALC_DATA);
 					}
 					
+					/* copy on write tag is needed (for the armature), or else no refresh happens */
+					DEG_id_tag_update(&arm->id, DEG_TAG_COPY_ON_WRITE);
 				}
 			}
 		}