title: How to reference environmental variables in WORKSPACE?
body: <p>If a project has an external dependency to software that's installed locally and can't be managed with <code>new_http_archive</code> or <code>new_git_repository</code> because licensing or size issues prevent it from being downloaded, is there a way to have the path specified with <code>new_local_repository</code> use an environmental variable?</p>
  
  <p>Looking at the <a href="https://github.com/bazelbuild/bazel/issues/746#issuecomment-169085318" rel="nofollow noreferrer">comments</a> on <a href="https://github.com/bazelbuild/bazel/issues/746" rel="nofollow noreferrer">Issue #746</a>, it looks like this was solved in some way. But I can't find any documentation on how to do it.</p>