Bug with updating a working copy through a symlink

Hi,

I have a symlink pointing to a "trunk" directory in a working copy.

When I do "svn up symlink", I get the following:
$ svn up memcache_plugin/
U memcache_plugin/_memcache.plugin.php
svn: In Verzeichnis 'memcache_plugin'
svn: Fehler beim Bearbeiten des Befehls 'modify-wcprop' in 'memcache_plugin'
svn: 'memcache_plugin' ist keine Arbeitskopie

After this, I cannot update anymore:
$ LANG=C svn up
svn: Working copy '.' locked
svn: run 'svn cleanup' to remove locks (type 'svn help cleanup' for details)

And "svn cleanup" (in the real directory) also fails:
$ LANG=C svn cleanup
svn: In directory 'memcache_plugin/trunk'
svn: Can't open
file 'memcache_plugin/trunk/.svn/tmp/text-base/_memcache.plugin.php.svn-base':
No such file or directory

Sorry, I don't have the original error message in english, but could provide
it, if it's necessary.

svn, version 1.3.0 (r17949)
   compiled Jan 18 2006, 02:46:02