Re: [PATCH v3 2/5] revision walk: optionally use sparse reachability

> Add another bit flag to the struct rev_info.
> 
> The only caller that uses this after this patch is builtin/pack-objects.
> Without this, sparsity seems to do little good therein, as
> prepare_revision_walk will densely propagate UNINTERESTING flags from
> trees to tree contents, before mark_edges_uninteresting has a chance to
> be faster by being sparse.
> 
> While here, drop the "sparse" parameter to mark_edges_uninteresting,
> introduced in 4f6d26b167 ("list-objects: consume sparse tree walk",
> 2019-01-16) which can now use the flag in struct rev_info.  No
> functional change intended.