title: svndumpfilter fails with "Invalid copy source path..." error
body: <p>I want to move part of my SVN repo offsite, onto an AWS instance &amp; am following this page (<a href="http://svnbook.red-bean.com/en/1.1/ch05s03.html" rel="noreferrer">Repository Maintenance</a>)</p>
  <p>I have taken a <code>dump</code> of the whole repo (Windows commands):</p>
  <ul>
  <li><code>svnadmin dump c:\repo &gt; all_repo</code></li>
  </ul>
  <p>Next is to filter it, to include only the project I am interested in (which is called &quot;M1&quot;).</p>
  <ul>
  <li><code>type all_repo | svndumpfilter include M1 --drop-empty-revs &gt; m1</code></li>
  </ul>
  <p>I know this is correct, as I have done it on some of the other projects already.</p>
  <hr />
  <p>On this project, it breaks with the error indicated in the title of this post. The exact wording is:</p>
  <blockquote>
  <p>svndumpfilter: Invalid copy source path '/Personal/Richard/M1_Config'</p>
  <p>The process tried to write to a nonexistent pipe.</p>
  </blockquote>
  <p>The folder that the error refers to is a configuration utility that I wrote and submitted under my personal folder, and it is not under the root/m1... folder at all. I do not want to include it in the filtered file, but do not know how to indicate this to the svn commands.</p>
  <ol>
  <li>How can I correctly filter for the whole M1 folder and its children, while excluding the Personal/Richard/M1_Config folder entirely?</li>
  <li>How can I be sure whether the exported file contains the correct information to correctly recreate the M1 folder on the remote SVN?</li>
  </ol>