'bzr break-lock' Fails on Cygwin

[Stefan Adelbert]

Running 'bzr break-lock' from cygwin causes the following stack trace:

$ bzr break-lock
bzr: ERROR: exceptions.TypeError: encode() argument 1 must be string, not None

Traceback (most recent call last):
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\commands.py", line 930, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\commands.py", line 1121, in run_bzr
    ret = run(*run_argv)
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\commands.py", line 673, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\commands.py", line 697, in run
    return self._operation.run_simple(*args, **kwargs)
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\cleanup.py", line 136, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\cleanup.py", line 166, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\builtins.py", line 5495, in run
    control.break_lock()
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\bzrdir.py", line 116, in break_lock
    thing_to_unlock.break_lock()
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\workingtree_4.py", line 201, in break_lock
    self._control_files.break_lock()
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\lockable_files.py", line 101, in break_lock
    self._lock.break_lock()
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\lockdir.py", line 411, in break_lock
    dict(lock_info=unicode(holder_info))):
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\ui\__init__.py", line 219, in confirm_action
    return self.get_boolean(prompt % prompt_kwargs)
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\ui\__init__.py", line 357, in get_boolean
    choice = self.choose(prompt + '?', '&yes\n&no', default=None)
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\ui\text.py", line 202, in choose
    return choose_ui.interact()
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\ui\text.py", line 140, in interact
    self.ui.prompt(self.prompt)
  File "C:\Program Files (x86)\bzr-2.6.0\bzrlib\ui\text.py", line 340, in prompt
    prompt = prompt.encode(self.stderr.encoding)
TypeError: encode() argument 1 must be string, not None

bzr 2.6.0 on python 2.7.5 (Windows-7-6.1.7601-SP1)
arguments: ['C:\\Program Files (x86)\\bzr-2.6.0\\bzr', 'break-lock']
plugins: bash_completion[2.6.0], changelog_merge[2.6.0], grep[2.6.0],
    launchpad[2.6.0], netrc_credential_store[2.6.0], news_merge[2.6.0],
    po_merge[2.6.0], qbzr[0.23.1], weave_fmt[2.6.0]
encoding: 'cp1252', fsenc: 'mbcs', lang: None

*** Bazaar has encountered an internal error. This probably indicates a
    bug in Bazaar. You can help us fix it by filing a bug report at
        https://bugs.launchpad.net/bzr/+filebug
    including this traceback and a description of the problem.

It appears to be related to the following bugs:
https://bugs.launchpad.net/bzr/+bug/70565
https://bugs.launchpad.net/bzr/+bug/90637

I modified bzrlib/ui/texy,py:341 (rev 6585) to include "TypeError", which seems to solve the problem:

        except (UnicodeError, AttributeError, TypeError):

I looks like the problem would still exist in 2.7.0.