message: test: wait rather than assert presence of file in startupnotify test
  Should fix
diff: @@ -26,7 +26,7 @@ class StartupNotifyTest(BitcoinTestFramework):
  self.log.info("Test -startupnotify command is run when node starts")
  self.restart_node(0, extra_args=[f"-startupnotify=echo '{FILE_NAME}' >> {NODE_DIR}/{FILE_NAME}"])
  - assert os.path.exists(tmpdir_file)
  + self.wait_until(lambda: os.path.exists(tmpdir_file))
  self.log.info("Test -startupnotify is executed once")
  with open(tmpdir_file, "r", encoding="utf8") as f:
  