`merge --interactive` blows up with traceback on non-ascii filenames

[Alexander Belchenko]

create non-ascii file in the branch with

python -c "open(u'\u00e0', 'wb').write('foo')"

add this file under version control, commit, then try to `bzr merge --interactive` from this branch. Get traceback:

bzr: ERROR: exceptions.UnicodeEncodeError: 'ascii' codec can't encode character u'\xe0' in position 10: ordinal not in range(128)

Traceback (most recent call last):
  File "C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\commands.py", line 909, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\commands.py", line 1107, in run_bzr
    ret = run(*run_argv)
  File "C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\commands.py", line 687, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\commands.py", line 702, in run
    return self._operation.run_simple(*args, **kwargs)
  File "C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\cleanup.py", line 122, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\cleanup.py", line 156, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\builtins.py", line 3868, in run
    return self._do_interactive(merger)
  File "C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\builtins.py", line 3912, in _do_interactive
    shelver.run()
  File "C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\shelf_ui.py", line 201, in run
    if self.prompt_bool(self.reporter.prompt_change(change)):
  File "C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\shelf_ui.py", line 286, in prompt_bool
    char = self.prompt(question + prompt)
  File "C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\shelf_ui.py", line 261, in prompt
    sys.stdout.write(message)
UnicodeEncodeError: 'ascii' codec can't encode character u'\xe0' in position 10: ordinal not in range(128)

bzr 2.2.0dev1 on python 2.5.4 (Windows-XP-5.1.2600-SP3)
arguments: ['C:\\work\\Bazaar\\bzr-2a\\bzr.dev\\bzr', 'merge', '--interactive']
encoding: 'cp1251', fsenc: 'mbcs', lang: 'ru'
plugins:
  acad C:\work\Bazaar\plugins\acad [0.8.0]
  bash_completion C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\plugins\bash_completion [2.2.0dev1]
  colo C:\work\Bazaar\plugins\colo [0.0.3dev]
  explorer C:\work\Bazaar\plugins\explorer [1.0.2dev]
  format1 C:\work\Bazaar\plugins\format1 [unknown]
  launchpad C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\plugins\launchpad [2.2.0dev1]
  netrc_credential_store C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\plugins\netrc_credential_store [2.2.0dev1]
  news_merge C:\work\Bazaar\bzr-2a\bzr.dev\bzrlib\plugins\news_merge [2.2.0dev1]
  qbzr C:\work\Bazaar\plugins\qbzr [0.19.0dev1]
  scmproj C:\work\Bazaar\plugins\scmproj [0.6.1]
  x_bit C:\work\Bazaar\plugins\x_bit [1.0.0]

*** 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.
bzr: warning: some compiled extensions could not be loaded; see <https://answers.launchpad.net/bzr/+faq/703>