title: info files in subdirectory is not recognized in emacs
body: <p>I installed an additional info file using</p>
  
  <pre><code>install-info /usr/share/info/asymptote/asymptote.info.gz /usr/share/info/dir
  </code></pre>
  
  <p>it is perfectly visible by <code>info</code> command from the command line, i.e. <code>info asymptote</code> return content of asymptote/asymptote.info.gz properly. Also it is visible by emacs in the top node when I use <code>M-x info</code> command, but when I try to go to <code>asymptote</code> node, it complains "Info-find-file: Info file asymptote does not exist". The problem looks similar to <a href="https://stackoverflow.com/questions/8122214/info-indexing-within-and-without-emacs">info indexing (within and without emacs)</a> although it is not quite the same. It seems that info command in emacs does not recognize the subdirectory, while the original <code>info</code> command does. Is it possible to force emacs behave in the same way?</p>