aptdaemon failed while running Update Manager

[dbroomex]

Stack trace is below. It is very similar to bug #589273 but the source line numbers are not the same. Happened while updating Maverick.

Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/aptdaemon/worker.py", line 171, in _process_transaction
    self.commit_packages(*self.trans.packages)
  File "/usr/lib/python2.6/dist-packages/aptdaemon/worker.py", line 218, in commit_packages
    self._commit_changes()
  File "/usr/lib/python2.6/dist-packages/aptdaemon/worker.py", line 660, in _commit_changes
    self._cache.commit(fetch_progress, inst_progress)
  File "/usr/lib/python2.6/dist-packages/apt/deprecation.py", line 98, in deprecated_function
    return func(*args, **kwds)
  File "/usr/lib/python2.6/dist-packages/apt/cache.py", line 409, in commit
    res = self.install_archives(pm, install_progress)
  File "/usr/lib/python2.6/dist-packages/apt/deprecation.py", line 98, in deprecated_function
    return func(*args, **kwds)
  File "/usr/lib/python2.6/dist-packages/apt/cache.py", line 376, in install_archives
    install_progress.finish_update()
  File "/usr/lib/python2.6/dist-packages/aptdaemon/progress.py", line 260, in finish_update
    lock.system.acquire()
  File "/usr/lib/python2.6/dist-packages/aptdaemon/lock.py", line 102, in acquire
    self.fd = get_lock_fd(self.path)
  File "/usr/lib/python2.6/dist-packages/aptdaemon/lock.py", line 89, in get_lock_fd
    raise LockFailedError(lock_path, process)
LockFailedError