Pathname#mountpoint?

# File tmp/rubies/ruby-4.0.0/pathname_builtin.rb, line 510
def mountpoint?
  begin
    stat1 = self.lstat
    stat2 = self.parent.lstat
    stat1.dev != stat2.dev || stat1.ino == stat2.ino
  rescue Errno::ENOENT
    false
  end
end