can not stop standalone cluster

[dttlgotv]

I can start standalone cluster well, but when I stop it, the error is below:

heron-admin standalone cluster stop
Are you sure you want to stop the cluster? This will terminate everything running in the cluster and remove any scheduler state. (yes/no): yes
Traceback (most recent call last):
File ".bootstrap/_pex/pex.py", line 365, in execute
File ".bootstrap/_pex/pex.py", line 293, in _wrap_coverage
File ".bootstrap/_pex/pex.py", line 325, in _wrap_profiling
File ".bootstrap/_pex/pex.py", line 408, in _execute
File ".bootstrap/_pex/pex.py", line 466, in execute_entry
File ".bootstrap/_pex/pex.py", line 471, in execute_module
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/runpy.py", line 180, in run_module
fname, loader, pkg_name)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/runpy.py", line 72, in _run_code
exec code in run_globals
File "heron/tools/admin/src/python/main.py", line 182, in
sys.exit(main())
File "heron/tools/admin/src/python/main.py", line 178, in main
return execute(command_handlers)
File "heron/tools/admin/src/python/main.py", line 170, in execute
results = run(handlers, command, parser, command_line_args, unknown_args)
File "heron/tools/admin/src/python/main.py", line 102, in run
return handlers[command].run(command, parser, command_args, unknown_args)
File "heron/tools/admin/src/python/standalone.py", line 177, in run
if check_sure(cl_args, "Are you sure you want to stop the cluster?"
File "heron/tools/admin/src/python/standalone.py", line 862, in check_sure
yes = input("%s" % prompt + ' (yes/no): ')
File "", line 1, in
NameError: name 'yes' is not defined