title: Wand Policy Error: error/constitute.c/ReadImage/412
body: <p>I am facing the issue while converting pdf to image using Wand:</p>
  <pre><code>E           wand.exceptions.PolicyError: not authorized `/opt/sample.pdf' @ error/constitute.c/ReadImage/412
  </code></pre>
  <p>I have already visited the previous stack overflow question here:
  <a href="https://stackoverflow.com/questions/42928765/convertnot-authorized-aaaa-error-constitute-c-readimage-453">convert:not authorized `aaaa` @ error/constitute.c/ReadImage/453</a></p>
  <p>Here is my code</p>
  <pre><code>def build_image(self, pdf_path, img_path):
      with wand.image.Image(filename=pdf_path) as img:
          img.save(filename=img_path)
  </code></pre>
  <p>My code was working from last 6 months. Now, why am I getting this error?</p>
  <p>Please help.</p>