message: docker: Add workdir to DockerFile wrapper.
diff: @@ -86,6 +86,9 @@ class DockerFile(drake.Node):
  def env(self, k, v):
  self.__steps.append(('ENV', '{} {}'.format(k, v)))
  + def workdir(self, path):
  + self.__steps.append(('WORKDIR', path))
  +
  @property
  def image(self):
  return self.__image
  