Revert "Store new malloced value instead."
This reverts commit a9693064380ac62005cdd28f22b447902644a72f.
As mentioned in [LysLysKOM 20949405] (which probably hasn't been
exported correctly to the mailinglist yet):
The old code looks correct to me.
* Restore s->s->len to the value it had when s->s was allocated
* Reallocate s->s with the new (now known) final length.
The question does however arise whether the code is correct on