revision: parse parent in indegree_walk_step()

In indegree_walk_step(), we add unvisited parents to the indegree queue.
However, parents are not guaranteed to be parsed. As the indegree queue
sorts by generation number, let's parse parents before inserting them to
ensure the correct priority order.

Signed-off-by: Abhishek Kumar <[email protected]>
Reviewed-by: Taylor Blau <[email protected]>
Reviewed-by: Derrick Stolee <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: abhishekkumar2718

revision.c

@@ -3373,6 +3373,9 @@ static void indegree_walk_step(struct rev_info *revs)
 		struct commit *parent = p->item;
 		int *pi = indegree_slab_at(&info->indegree, parent);
 
+		if (repo_parse_commit_gently(revs->repo, parent, 1) < 0)
+			return;
+
 		if (*pi)
 			(*pi)++;
 		else