title: Nginx password protect root, and separate password for subdirectory
body: <p>I'm trying to set up basic HTTP authentication with Nginx that's multi-layered.  I'd like to have one username &amp; password for the entire site except for a certain subdirectory (URL), and a separate username &amp; password for that subdirectory.  If somebody navigates to that subdirectory, I want them to be prompted for the subdirectory-specific credentials only, and not the ones for the site root.</p>
  
  <p>How do I set this up?</p>