Bench update v11 fails yarn issue

Install / Update
17

Still bench update fails with the below error.

Traceback (most recent call last):
  File "/usr/local/bin/bench", line 11, in <module>
    load_entry_point('bench', 'console_scripts', 'bench')()
  File "/home/frappe/.bench/bench/cli.py", line 40, in cli
    bench_command()
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 764, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 717, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 956, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/home/frappe/.bench/bench/commands/update.py", line 32, in update
    patches.run(bench_path='.')
  File "/home/frappe/.bench/bench/patches/__init__.py", line 21, in run
    result = execute(bench_path)
  File "/home/frappe/.bench/bench/patches/v4/install_yarn.py", line 5, in execute
    exec_cmd('npm install yarn', os.path.join(bench_path, 'apps/frappe'))
  File "/home/frappe/.bench/bench/utils.py", line 159, in exec_cmd
    raise CommandFailedError(cmd)
bench.utils.CommandFailedError: npm install yarn