Meld crashes if svn working dir contains svn externals dirs

Binary package hint: meld

If I run meld in a SVN working copy to display local modifications, meld crashes if the working copy contains a SVN externals directory.

TESTCASE:
svnadmin create /tmp/test-repo
svn co file:///tmp/test-repo repo
cd repo
echo "bla" > file
svn add file
svn commit
svn cp file new-copy; meld .

The following traceback is given:
Traceback (most recent call last):
  File "/usr/lib/meld/meld/task.py", line 130, in iteration
    ret = task()
  File "/usr/lib/meld/meld/vcview.py", line 330, in _search_recursively_iter
    entries = filter(showable, self.vc.listdir(root))
  File "/usr/lib/meld/meld/vc/_vc.py", line 166, in listdir
    dirs, files = self.lookup_files(cdirs, cfiles)
  File "/usr/lib/meld/meld/vc/_vc.py", line 175, in lookup_files
    return self._get_dirsandfiles(directory, dirs, files)
  File "/usr/lib/meld/meld/vc/svn.py", line 105, in _get_dirsandfiles
    for match in self._get_matches(directory):
  File "/usr/lib/meld/meld/vc/svn.py", line 95, in _get_matches
    rev = status.attrib["revision"]
KeyError: 'revision'

regression potential:
low, small easily backported fix
The fix was released in 1.5.1 in oneiric and there are no reported regressions.

System info: Natty on amd64. meld 1.5.0-0ubuntu1