Re: [PATCH 09/14] refs/iterator: implement seeking for merged iterators

> Implement seeking on merged iterators. The implementation is rather
> straight forward, with the only exception that we must not deallocate
> the underlying iterators once they have been exhausted.
>
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  refs/iterator.c | 38 +++++++++++++++++++++++++++++---------
>  1 file changed, 29 insertions(+), 9 deletions(-)
>
> diff --git a/refs/iterator.c b/refs/iterator.c
> index 757b105261a..63608ef9907 100644
> --- a/refs/iterator.c
> +++ b/refs/iterator.c
> @@ -96,7 +96,8 @@ int is_empty_ref_iterator(struct ref_iterator *ref_iterator)
>  struct merge_ref_iterator {
>  	struct ref_iterator base;
>
> -	struct ref_iterator *iter0, *iter1;
> +	struct ref_iterator *iter0, *iter0_owned;
> +	struct ref_iterator *iter1, *iter1_owned;
>
>  	ref_iterator_select_fn *select;
>  	void *cb_data;
> @@ -160,13 +161,11 @@ static int merge_ref_iterator_advance(struct ref_iterator *ref_iterator)
>  	if (!iter->current) {
>  		/* Initialize: advance both iterators to their first entries */
>  		if ((ok = ref_iterator_advance(iter->iter0)) != ITER_OK) {
> -			ref_iterator_free(iter->iter0);
>  			iter->iter0 = NULL;