$ echo -e "1\n2" >file_a; echo 1 >file_b; meld file_a file_b

** (meld:509): WARNING **: Couldn't register with accessibility bus: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/meld/meldapp.py", line 73, in do_command_line
    tab = self.parse_args(command_line)
  File "/usr/lib/python2.7/dist-packages/meld/meldapp.py", line 316, in parse_args
    focus=i == 0)
  File "/usr/lib/python2.7/dist-packages/meld/meldapp.py", line 148, in open_files
    return window.open_paths(paths, **kwargs)
  File "/usr/lib/python2.7/dist-packages/meld/meldwindow.py", line 729, in open_paths
    paths, auto_compare=auto_compare, auto_merge=auto_merge)
  File "/usr/lib/python2.7/dist-packages/meld/meldwindow.py", line 678, in append_diff
    paths, merge_output=merge_output, meta=meta)
  File "/usr/lib/python2.7/dist-packages/meld/meldwindow.py", line 645, in append_filediff
    doc = filediff.FileDiff(len(files))
  File "/usr/lib/python2.7/dist-packages/meld/filediff.py", line 235, in __init__
    self._cached_match = CachedSequenceMatcher()
  File "/usr/lib/python2.7/dist-packages/meld/filediff.py", line 72, in __init__
    None, matchers.init_worker, maxtasksperchild=1)
  File "/usr/lib/python2.7/multiprocessing/__init__.py", line 232, in Pool
    return Pool(processes, initializer, initargs, maxtasksperchild)
  File "/usr/lib/python2.7/multiprocessing/pool.py", line 138, in __init__
    self._setup_queues()
  File "/usr/lib/python2.7/multiprocessing/pool.py", line 234, in _setup_queues
    self._inqueue = SimpleQueue()
  File "/usr/lib/python2.7/multiprocessing/queues.py", line 352, in __init__
    self._rlock = Lock()
  File "/usr/lib/python2.7/multiprocessing/synchronize.py", line 147, in __init__
    SemLock.__init__(self, SEMAPHORE, 1, 1)
  File "/usr/lib/python2.7/multiprocessing/synchronize.py", line 75, in __init__
    sl = self._semlock = _multiprocessing.SemLock(kind, value, maxvalue)
OSError: [Errno 13] Permission denied

