Set the cleanup on the post-growth vector, not the temporary one.

Author: graydon

src/comp/middle/trans.rs

@@ -2470,10 +2470,11 @@ fn trans_vec_add(@block_ctxt cx, @ty.t t,
                  ValueRef lhs, ValueRef rhs) -> result {
     auto r = alloc_ty(cx, t);
     auto tmp = r.val;
-    find_scope_cx(cx).cleanups += clean(bind drop_ty(_, tmp, t));
     r = copy_ty(r.bcx, INIT, tmp, lhs, t);
     auto bcx = trans_vec_append(r.bcx, t, tmp, rhs).bcx;
-    ret res(bcx, load_scalar_or_boxed(bcx, tmp, t));
+    tmp = load_scalar_or_boxed(bcx, tmp, t);
+    find_scope_cx(cx).cleanups += clean(bind drop_ty(_, tmp, t));
+    ret res(bcx, tmp);
 }