Running 'bzr pack' returns:

bzr: ERROR: zlib.error: Error -3 while decompressing: incorrect data check                                                                                                           

Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 831, in exception_to_return_code
    return the_callable(*args, **kwargs)                                                           
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 1026, in run_bzr                
    ret = run(*run_argv)                                                                           
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 643, in run_argv_aliases        
    return self.run(**all_cmd_args)                                                                
  File "/usr/lib/python2.5/site-packages/bzrlib/builtins.py", line 4164, in run                    
    repository.pack()                                                                              
  File "/usr/lib/python2.5/site-packages/bzrlib/decorators.py", line 192, in write_locked          
    result = unbound(self, *args, **kwargs)                                                        
  File "/usr/lib/python2.5/site-packages/bzrlib/repofmt/pack_repo.py", line 2357, in pack          
    self._pack_collection.pack()                                                                   
  File "/usr/lib/python2.5/site-packages/bzrlib/repofmt/pack_repo.py", line 1580, in pack          
    self._execute_pack_operations(pack_operations, OptimisingPacker)                               
  File "/usr/lib/python2.5/site-packages/bzrlib/repofmt/groupcompress_repo.py", line 584, in _execute_pack_operations
    packer.pack()                                                                                                    
  File "/usr/lib/python2.5/site-packages/bzrlib/repofmt/pack_repo.py", line 754, in pack                             
    return self._create_pack_from_packs()                                                                            
  File "/usr/lib/python2.5/site-packages/bzrlib/repofmt/groupcompress_repo.py", line 459, in _create_pack_from_packs 
    self._copy_text_texts()                                                                                          
  File "/usr/lib/python2.5/site-packages/bzrlib/repofmt/groupcompress_repo.py", line 442, in _copy_text_texts        
    'text', self._get_progress_stream, 4)                                                                            
  File "/usr/lib/python2.5/site-packages/bzrlib/repofmt/groupcompress_repo.py", line 394, in _copy_stream            
    reuse_blocks=False):                                                                                             
  File "/usr/lib/python2.5/site-packages/bzrlib/groupcompress.py", line 1451, in _insert_record_stream               
    bytes = record.get_bytes_as('fulltext')                                                                          
  File "/usr/lib/python2.5/site-packages/bzrlib/groupcompress.py", line 419, in get_bytes_as                         
    self._manager._prepare_for_extract()                                                                             
  File "/usr/lib/python2.5/site-packages/bzrlib/groupcompress.py", line 512, in _prepare_for_extract                 
    self._block._ensure_content(self._last_byte)                                                                     
  File "/usr/lib/python2.5/site-packages/bzrlib/groupcompress.py", line 196, in _ensure_content                      
    remaining_decomp, needed_bytes + _ZLIB_DECOMP_WINDOW)                                                            
error: Error -3 while decompressing: incorrect data check