Based on http://stackoverflow.com/questions/116074/how-to-ignore-a-directory-with-svn I tried
svn propset svn:ignore /foo/bar/ .
But when doing svn update /foo
I get this error:
svn: PROPFIND request failed on '/foo/bar/'
svn: PROPFIND of '/foo/bar': 405 Method Not Allowed (http://svn.assembla.com)
The reason why I am trying to skip /foo/bar is because I replaced it with a symlink to /some/other/dir
ln -s /some/other/dir /foo/bar