title: missing redis library when redis is installed
body: <p>I have redis and celery python libraries installed. I have redis server installed and running. using bash i can run <code>python</code> and <code>import redis</code> without errors. I have python-celery-common installed. I am using PyCharm and WSL. For some reason when i create tasks.py and try to run <code>celery -A tasks worker --loglevel=info
  </code> in bash i get the following stack trace (note the python3 in the path to celery when i am running python 2.7 - i have a feeling this is important but not sure how, or how to change):</p>
  
  <pre><code>Traceback (most recent call last):
    File "/usr/bin/celery", line 26, in &lt;module&gt;
      load_entry_point("celery", "console_scripts", "celery")()
    File "/usr/lib/python3/dist-packages/celery/__main__.py", line 14, in main
      _main()
    File "/usr/lib/python3/dist-packages/celery/bin/celery.py", line 326, in main
      cmd.execute_from_commandline(argv)
    File "/usr/lib/python3/dist-packages/celery/bin/celery.py", line 488, in execute_from_commandline
      super(CeleryCommand, self).execute_from_commandline(argv)))
    File "/usr/lib/python3/dist-packages/celery/bin/base.py", line 281, in execute_from_commandline
      return self.handle_argv(self.prog_name, argv[1:])
    File "/usr/lib/python3/dist-packages/celery/bin/celery.py", line 480, in handle_argv
      return self.execute(command, argv)
    File "/usr/lib/python3/dist-packages/celery/bin/celery.py", line 412, in execute
      ).run_from_argv(self.prog_name, argv[1:], command=argv[0])
    File "/usr/lib/python3/dist-packages/celery/bin/worker.py", line 221, in run_from_argv
      return self(*args, **options)
    File "/usr/lib/python3/dist-packages/celery/bin/base.py", line 244, in __call__
      ret = self.run(*args, **kwargs)
    File "/usr/lib/python3/dist-packages/celery/bin/worker.py", line 255, in run
      **kwargs)
    File "/usr/lib/python3/dist-packages/celery/worker/worker.py", line 99, in __init__
      self.setup_instance(**self.prepare_args(**kwargs))
    File "/usr/lib/python3/dist-packages/celery/worker/worker.py", line 122, in setup_instance
      self.should_use_eventloop() if use_eventloop is None
    File "/usr/lib/python3/dist-packages/celery/worker/worker.py", line 241, in should_use_eventloop
      self._conninfo.transport.implements.async and
    File "/usr/lib/python3/dist-packages/kombu/connection.py", line 832, in transport
      self._transport = self.create_transport()
    File "/usr/lib/python3/dist-packages/kombu/connection.py", line 576, in create_transport
      return self.get_transport_cls()(client=self)
    File "/usr/lib/python3/dist-packages/kombu/transport/redis.py", line 1009, in __init__
      raise ImportError('Missing redis library (pip install redis)')
  ImportError: Missing redis library (pip install redis)
  </code></pre>
  
  <p>output from bash when i run <code>python</code>:</p>
  
  <pre><code>Python 2.7.15rc1 (default, Nov 12 2018, 14:31:15)
  [GCC 7.3.0] on linux2
  Type "help", "copyright", "credits" or "license" for more information.
  </code></pre>
  
  <p>output from <code>pip freeze</code></p>
  
  <pre><code> amqp==2.3.2
  asn1crypto==0.24.0
  billiard==3.5.0.5
  celery==4.2.1
  cryptography==2.1.4
  Django==1.11.11
  djangorestframework==3.9.0
  enum34==1.1.6
  idna==2.6
  ipaddress==1.0.17
  keyring==10.6.0
  keyrings.alt==3.0
  kombu==4.2.2
  psycopg2==2.7.4
  pycrypto==2.6.1
  pygobject==3.26.1
  pytz==2018.7
  pyxdg==0.25
  redis==3.0.1
  SecretStorage==2.3.1
  six==1.11.0
  sqlparse==0.2.4
  vine==1.1.4
  </code></pre>