Merge branch 'jk/list-objects-optim-wo-trees'

The object traversal machinery has been optimized not to load tree
objects when we are only interested in commit history.

* jk/list-objects-optim-wo-trees:
  list-objects: don't queue root trees unless revs->tree_objects is set

list-objects.c

@@ -365,7 +365,9 @@ static void do_traverse(struct traversal_context *ctx)
 		 * an uninteresting boundary commit may not have its tree
 		 * parsed yet, but we are not going to show them anyway
 		 */
-		if (get_commit_tree(commit)) {
+		if (!ctx->revs->tree_objects)
+			; /* do not bother loading tree */
+		else if (get_commit_tree(commit)) {
 			struct tree *tree = get_commit_tree(commit);
 			tree->object.flags |= NOT_USER_GIVEN;
 			add_pending_tree(ctx->revs, tree);