juju-deployer breaks when "env python" is python2.7

Hi,

We have a trusty server where "env python" resolves to python2.7.

We have the following juju-deployer packages installed :

ii juju-deployer 1:0.9.2~bzr203~60~2.IS.14.04 amd64 A transitional package which depends on python-juju-deployer.
ii python-juju-deployer 1:0.9.2~bzr203~60~2.IS.14.04 amd64 A tool to deploy complex stacks of services using juju.
ii python3-juju-deployer 1:0.9.2~bzr203~60~2.IS.14.04 amd64 A tool to deploy complex stacks of services using juju.

However, when one runs /usr/bin/juju-deployer (which is python3), it complains about TLS stuff, because it's actually running the 2.7 version underneath. Example trace :

/usr/lib/python2.7/dist-packages/jujuclient/connector.py:18: RuntimeWarning: This version of Python does not support TLSv1.2. Please use Python 2.7.9+ or 3.4+ instead. Attempting to use TLSv1 - may not work with all versions of Juju.
  'all versions of Juju.', RuntimeWarning)
/usr/lib/python2.7/dist-packages/jujuclient/connector.py:18: RuntimeWarning: This version of Python does not support TLSv1.2. Please use Python 2.7.9+ or 3.4+ instead. Attempting to use TLSv1 - may not work with all versions of Juju.
  'all versions of Juju.', RuntimeWarning)
Traceback (most recent call last):
  File "/usr/bin/juju-deployer", line 9, in <module>
    load_entry_point('juju-deployer==0.9.2', 'console_scripts', 'juju-deployer')()
  File "/usr/lib/python2.7/dist-packages/deployer/cli.py", line 140, in main
    run()
  File "/usr/lib/python2.7/dist-packages/deployer/cli.py", line 245, in run
    diff.Diff(env, deployment, options).run()
  File "/usr/lib/python2.7/dist-packages/deployer/action/diff.py", line 158, in run
    diff = self.do_diff()
  File "/usr/lib/python2.7/dist-packages/deployer/action/diff.py", line 152, in do_diff
    self.env.connect()
  File "/usr/lib/python2.7/dist-packages/deployer/env/go.py", line 78, in connect
    self.client = self.client_class.connect(self.name)
  File "/usr/lib/python2.7/dist-packages/jujuclient/environment.py", line 87, in connect
    return connector().run(cls, env_name)
  File "/usr/lib/python2.7/dist-packages/jujuclient/connector.py", line 51, in run
    cert_path, data.get('environ-uuid'))
  File "/usr/lib/python2.7/dist-packages/jujuclient/connector.py", line 59, in connect_env
    env = cls(endpoint, name=name, ca_cert=cert_path, env_uuid=env_uuid)
  File "/usr/lib/python2.7/dist-packages/jujuclient/juju2/environment.py", line 15, in __init__
    super(Environment, self).__init__(*args, **kw)
  File "/usr/lib/python2.7/dist-packages/jujuclient/environment.py", line 41, in __init__
    endpoint, self._ca_cert)
  File "/usr/lib/python2.7/dist-packages/jujuclient/connector.py", line 71, in connect_socket
    endpoint, origin=endpoint, sslopt=sslopt)
  File "/usr/lib/python2.7/dist-packages/websocket/_core.py", line 219, in create_connection
    websock.connect(url, **options)
  File "/usr/lib/python2.7/dist-packages/websocket/_core.py", line 463, in connect
    self.sock = ssl.wrap_socket(self.sock, **sslopt)
  File "/usr/lib/python2.7/ssl.py", line 487, in wrap_socket
    ciphers=ciphers)
  File "/usr/lib/python2.7/ssl.py", line 243, in __init__
    self.do_handshake()
  File "/usr/lib/python2.7/ssl.py", line 405, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLError: [Errno 1] _ssl.c:510: error:1409442E:SSL routines:SSL3_READ_BYTES:tlsv1 alert protocol version
2016-11-24 13:11:35 [ERROR] Error calling external process

From the first few lines, you can see that python2.7 is called :
Traceback (most recent call last):
  File "/usr/bin/juju-deployer", line 9, in <module>
    load_entry_point('juju-deployer==0.9.2', 'console_scripts', 'juju-deployer')()
  File "/usr/lib/python2.7/dist-packages/deployer/cli.py", line 140, in main
    run()

even though :
$ head -n1 /usr/bin/juju-deployer
#!/usr/bin/python3

Thanks