bzr crashed with ImportError in /usr/lib/python2.6/dist-packages/bzrlib/plugins/fastimport/branch_updater.py: cannot import name error

running fast-import plugin.

ProblemType: Crash
DistroRelease: Ubuntu 11.04
Package: bzr 2.4.1-1ubuntu1 [modified: usr/bin/bzr]
ProcVersionSignature: Ubuntu 2.6.38-13.52-generic-pae 2.6.38.8
Uname: Linux 2.6.38-13-generic-pae i686
Architecture: i386
BzrDebugFlags: set()
BzrVersion: 2.6b1
CommandLine: ['/usr/local/bin/bzr', 'fast-import', '/tmp/export.fi']
CrashDB: bzr
CrashDb: bzr
Date: Fri Mar 30 16:46:58 2012
ExecutablePath: /usr/bin/bzr
FileSystemEncoding: UTF-8
InstallationMedia: Ubuntu-Netbook-Remix 9.10 "Karmic Koala" - Release i386 (20091028.4)
InterpreterPath: /usr/bin/python2.6
Locale: en_US.UTF-8
PackageArchitecture: all
Platform: Linux-2.6.38-13-generic-pae-i686-with-Ubuntu-11.04-natty
ProcCmdline: /usr/bin/python /usr/local/bin/bzr fast-import /tmp/export.fi
ProcEnviron:
 SHELL=/bin/bash
 PATH=(custom, user)
 LANG=en_US.UTF-8
PythonVersion: 2.6.6
SourcePackage: bzr
Title: bzr crashed with ImportError in /usr/lib/python2.6/dist-packages/bzrlib/plugins/fastimport/branch_updater.py: cannot import name error
UpgradeStatus: No upgrade log present (probably fresh install)
UserEncoding: utf-8
UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare

Traceback (most recent call last):
  File "/usr/local/lib/python2.6/dist-packages/bzr-2.6b1-py2.6-linux-i686.egg/bzrlib/commands.py", line 930, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/bzr-2.6b1-py2.6-linux-i686.egg/bzrlib/commands.py", line 1141, in run_bzr
    ret = run(*run_argv)
  File "/usr/local/lib/python2.6/dist-packages/bzr-2.6b1-py2.6-linux-i686.egg/bzrlib/commands.py", line 673, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/local/lib/python2.6/dist-packages/bzr-2.6b1-py2.6-linux-i686.egg/bzrlib/commands.py", line 697, in run
    return self._operation.run_simple(*args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/bzr-2.6b1-py2.6-linux-i686.egg/bzrlib/cleanup.py", line 136, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/bzr-2.6b1-py2.6-linux-i686.egg/bzrlib/cleanup.py", line 166, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/fastimport/cmds.py", line 279, in run
    from bzrlib.plugins.fastimport.processors import generic_processor
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/fastimport/processors/generic_processor.py", line 38, in <module>
    from bzrlib.plugins.fastimport import (
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/fastimport/branch_updater.py", line 22, in <module>
    from bzrlib.trace import error, note
ImportError: cannot import name error