adjust for master changes

Ref: e8985f22711fe9a342b27a10052ae3655f64435c

src/vmod_blobdigest.c

@@ -308,9 +308,11 @@ get_scope(const struct vrt_ctx * const restrict ctx,
 			return NULL;
 		}
 
-		assert(ctx->req->top);
 		priv = VRT_priv_top(ctx, (void *)h);
-		ws = ctx->req->top->ws;
+		if (ctx->req->top)
+			ws = ctx->req->top->topreq->ws;
+		else
+			ws = ctx->req->ws;
 		break;
 	}
 	default: