title: Escaping environment variable names in VSTS
body: <p>In my build configuration I have say <code>MY.VAR</code> variable defined on <strong>Variables</strong> tab. In VSTS all build variables are automatically available as environment variables accessible in task steps which is pretty nice. The problem is VSTS converts dot characters to underscores so <code>MY.VAR</code> becomes <code>MY_VAR</code> in environments variables. Which is just stupid as I can have any number of dots in my environment variables:</p>
  
  <pre><code>set MY.VAR=my-numeric-value
  </code></pre>
  
  <p>How to make VSTS to not convert dots to underscores? Any escaping trick? Or, how can I set <code>MY.VAR</code> environment variable so that it's available to every task in my build?</p>
  
  <p>I tried <code>${env:MY.VAR} = "my-numeric-value"</code> powershell command which works just fine but the variable is not persisted to the subsequent tasks.</p>