juju-wait 2.5.1 fails from bundletester

2.5.1 introduced an shutil.which call:

https://git.launchpad.net/juju-wait/commit/?id=df9d0a230cfe618acbd0b40c61b2f4fae1620d06

It seems this doesn't exist in py2. Bundletester is py2 and now fails like this:

...
2017-04-20 19:07:01 DEBUG Deploy of bundle completed.
2017-04-20 19:07:01 INFO Waiting for deployment to complete.
Traceback (most recent call last):
  File "/usr/local/bin/juju-wait", line 11, in <module>
    sys.exit(wait_cmd())
  File "/usr/local/lib/python2.7/dist-packages/juju_wait/__init__.py", line 236, in wait_cmd
    wait(log, args.wait_for_workload, max_wait)
  File "/usr/local/lib/python2.7/dist-packages/juju_wait/__init__.py", line 272, in wait
    status = get_status()
  File "/usr/local/lib/python2.7/dist-packages/juju_wait/__init__.py", line 134, in get_status
    json_status = run_or_die([juju_exe(), 'status', '--format=json'], env=env)
  File "/usr/local/lib/python2.7/dist-packages/juju_wait/__init__.py", line 102, in juju_exe
    if not shutil.which(juju):
AttributeError: 'module' object has no attribute 'which'
...

Would you consider creating a py2/3 compatible way to call 'which'?