Minor DRY tweak.

src/patricia.c

@@ -117,17 +117,13 @@ y_dup(struct pt_y *y0, unsigned short len)
 
 	assert(len < y0->len);
 
-	errno = 0;
-	ALLOC_OBJ(y, PT_Y_MAGIC);
+	y = y_alloc(y0->idx, y0->off + len, y0->len - len);
 	if (y == NULL)
 		return (NULL);
 
 	y->leaf[0] = y0->leaf[0];
 	y->leaf[1] = y0->leaf[1];
 	y->bitmask = y0->bitmask;
-	y->idx = y0->idx;
-	y->off = y0->off + len;
-	y->len = y0->len - len;
 	return (y);
 }