message: Seek to start when reading tilescan cache
diff: @@ -21,6 +21,7 @@ TileCache::TileCache(const std::string& filename, bool use_env) {
  }
  file_.exceptions(std::fstream::failbit | std::fstream::badbit);
  file_.open(openname, std::fstream::in | std::fstream::out | std::fstream::app);
  + file_.seekp(0);
  std::string line;
  file_.exceptions(std::fstream::badbit);
  while (std::getline(file_, line)) {
  