title: Trying to create a pre-commit hook that verify externals
body: <p>I am currently trying to create a pre-commit hook that prevent user to tag a version of code with external that are not tags. </p>
  
  <p>I am just trying to figure out a way to get the external that are specify in a transaction but cant figure out how. The command svnlook dont seem to be able to return anything that remotely look like externals modification. And with the svn command it seem to be the transaction that I am unable to specify. I have no idea what command to use in my pre-commit hook. I am currently in windows but making a python script to be able to test this on our linux server.</p>
  
  <p>What I tested so far is the following :</p>
  
  <pre><code>svnlook propget C:\TestReposLocal svn:externals &lt;== Give me error something is missing
  
  svn propget svn:externals C:\Test    &lt;== Give me externals but I cant figure out how to get this from a transaction to place in a pre-commit hook.
  </code></pre>
  
  <p>In my repository (C:\TestReposLocal) I have one external that is the trunk of another repository. This repository is displayed with the svn propget command but I need to know with the current transaction in a pre-commit if this external is something else than a Tag.</p>
  
  <p>Any help would be gladly receive.</p>
  
  <p>Tnx</p>