- don't leak node in both hash_table::bucket::erase()

- don't leak node in both hash_table::bucket::erase()
- remove bad code from hash_table::bucket::erase(const char *) that was
  introduced with the last patch. (This function isn't used anywhere and
  is scheduled for removal. Leaving it in for now as a reference.)
- remove leaves first in remove_from_path_caches()

- cosmetics: indentation, one trailing space, variable name change, comment
  (Sorrry for mixing that with actual code, but I think it's easy to see.)