title: shell env variables are not passed in docker-compose using jenkins
body: <p>To reproduce my issue:</p>
  
  <ol>
  <li>Create freestyle project in jenkins with one task 'execute shell' with this code:</li>
  </ol>
  
  <blockquote>
  <pre><code>export PROJECT_NAME=hello
  export IMAGE_NAME=hello-world
  docker-compose -p ${PROJECT_NAME} up
  </code></pre>
  </blockquote>
  
  <ol start="2">
  <li>Place docker-compose.yml in job's workspace:</li>
  </ol>
  
  <blockquote>
  <pre><code>version: '2'
  services:
    app:
      image: ${IMAGE_NAME}
  </code></pre>
  </blockquote>
  
  <ol start="3">
  <li>Run this job.</li>
  </ol>
  
  <p>I get error:</p>
  
  <pre><code>Started by user anonymous
  [EnvInject] - Loading node environment variables.
  Building in workspace /var/lib/jenkins/jobs/testenv/workspace
  [workspace] $ /bin/sh -xe /tmp/hudson1988957642163027988.sh
  + PROJECT_NAME=hello
  + IMAGE_NAME=hello-world
  + docker-compose -p hello up
  The IMAGE_NAME variable is not set. Defaulting to a blank string.
  </code></pre>
  
  <p>I created script with same code on my mac machine and it works!</p>
  
  <pre><code>Alexanders-Mini:deploy alexanderkondaurov$ ./test.sh 
  Creating hello_app_1
  Attaching to hello_app_1
  app_1  | 
  app_1  | Hello from Docker.
  app_1  | This message shows that your installation appears to be working correctly.
  </code></pre>
  
  <p>I don't understand why it doesn't work in jenkins. 
  As you see docker-compose doesn't see shell env variables :(</p>