title: Sparse checkouts and svn:externals
body: <p>I'm trying to do a sparse checkout of a folder containing externals, but none of the externals are being checked out. <a href="http://subversion.tigris.org/issues/show_bug.cgi?id=2954" rel="nofollow noreferrer">This issue</a> seems to indicate that this behavior may be by design, or at least that it isn't clear what the behavior should be. From my point of view, the obvious behavior is that externals are treated just as any other directory, and checked out following the same sparse checkout rules.</p>
  
  <p>Is there a way to work around this except manually checking out the externals?</p>