title: intersphinx link creation issues for local files across multiple projects
body: <p>I have a few different Sphinx projects that I would like to refer to each other locally (no web server). I have separate code + build directories setup for the projects and was trying out <code>intersphinx</code> to solve this requirement.</p>
  <p>My questions are:</p>
  <ol>
  <li><p>Is there a better way of referring to two or more local projects within Sphinx?</p>
  </li>
  <li><p>Is there a way to strip out the second build in the path?</p>
  </li>
  </ol>
  <p>In my configuration file I have:</p>
  <pre class="lang-py prettyprint-override"><code>intersphinx_mapping = {
      'doc1': ('../build/doc1',None)
  }
  </code></pre>
  <p>so I get no issues in doing a make HTML, however when I look at the reference I've created with <code>:ref:'doc1 info &lt;doc1:label1&gt;'</code> I have in the HTML document:</p>
  <p><code>file:///&lt;root path&gt;/build/**build**/doc1/html/doc.html#label1</code></p>
  <p>So the issue is I get two &quot;build&quot; directory listings - it should of been:</p>
  <p><code>file:///&lt;root path&gt;/build/doc1/html/doc.html#label1.</code></p>
  <p>If I manually do this, it correctly pulls in the document.</p>
  <p>I've also tried replacing <code>None</code> with <code>'../build/doc1'</code>.  If I drop the build from the mapping I do get an error in finding the <code>objects.inv</code> file for doc1.</p>
  <p>I do not want to use absolute path since the end user getting this documentation may see it in another location and I want this to be cross platform...</p>
  <p>My directory tree is essentially as follows:</p>
  <pre class="lang-none prettyprint-override"><code>Makefile
  build/doc1/html
  build/doc2/html
  doc1
  doc2
  </code></pre>
  <p>As a background, I'm trying this under Cygwin with Sphinx 1.7.5... I haven't tried Linux yet to see if I get the same behavior...</p>