title: Plan - Pass a var-file in a different directory to plan
body: <p>Using Terraform v0.11.11, when invoking terraform plan, supply a .tfvars file that is NOT in the current directory e.g a common 'global' file for global constants</p>
  
  <p>seems to just ignore it when I try ../ in an var-file option</p>
  
  <pre><code>-var-file="../$(ENV).global.tfvars"
  </code></pre>
  
  <p>What options do I have to achieve a similar result if this is not possible (event in the v0.12 is this still the case)?</p>