delta-islands: use repo_parse_tree()

19be71d (delta-islands: stop depending on `the_repository`,
2025-03-10) replaced explicit uses of the_repository.  parse_tree() uses
it internally, though, so call repo_parse_tree() instead and hand it the
correct repository.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: rscharfe

delta-islands.c

@@ -283,7 +283,7 @@ void resolve_tree_islands(struct repository *r,
 		root_marks = kh_value(island_marks, pos);
 
 		tree = lookup_tree(r, &ent->idx.oid);
-		if (!tree || parse_tree(tree) < 0)
+		if (!tree || repo_parse_tree(r, tree) < 0)
 			die(_("bad tree object %s"), oid_to_hex(&ent->idx.oid));
 
 		init_tree_desc(&desc, &tree->object.oid, tree->buffer, tree->size);