Scandic letters disrupt Bazaar's FastExport

I am based on Scandinavia and therefore constantly need to use the Scandic letters 'ä' and 'ö' in my writing and in naming files. This seems to cause a codec incompatibility when attempting to export the Bazaar database with "bzr fast-export --no-plain . > fast-export.db". This command fails with the following error message:

23:21:57 Calculating the revisions to include ...
23:21:57 Starting export of 197 revisions ...
bzr: ERROR: exceptions.UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 29: ordinal not in range(128)

Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/bzrlib/commands.py", line 930, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/bzrlib/commands.py", line 1121, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.7/site-packages/bzrlib/commands.py", line 673, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.7/site-packages/bzrlib/commands.py", line 697, in run
    return self._operation.run_simple(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/bzrlib/cleanup.py", line 136, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/bzrlib/cleanup.py", line 166, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/bzrlib/plugins/fastimport/cmds.py", line 720, in run
    return exporter.run()
  File "/usr/lib/python2.7/site-packages/bzrlib/plugins/fastimport/exporter.py", line 240, in run
    self.emit_commit(revid, self.ref)
  File "/usr/lib/python2.7/site-packages/bzrlib/plugins/fastimport/exporter.py", line 358, in emit_commit
    self.print_cmd(self._get_commit_command(ref, mark, revobj, file_cmds))
  File "/usr/lib/python2.7/site-packages/bzrlib/plugins/fastimport/exporter.py", line 287, in print_cmd
    self.outf.write("%r\n" % cmd)
  File "/usr/lib/python2.7/site-packages/fastimport/commands.py", line 74, in __repr__
    return self.__bytes__()
  File "/usr/lib/python2.7/site-packages/fastimport/commands.py", line 189, in __bytes__
    return self.to_string(include_file_contents=True)
  File "/usr/lib/python2.7/site-packages/fastimport/commands.py", line 242, in to_string
    for c in self.iter_files()])
  File "/usr/lib/python2.7/site-packages/fastimport/helpers.py", line 118, in repr_bytes
    return repr(obj)
  File "/usr/lib/python2.7/site-packages/fastimport/commands.py", line 74, in __repr__
    return self.__bytes__()
  File "/usr/lib/python2.7/site-packages/fastimport/commands.py", line 367, in __bytes__
    return self.to_string(include_file_contents=True)
  File "/usr/lib/python2.7/site-packages/fastimport/commands.py", line 399, in to_string
    [b'M', self._format_mode(self.mode), dataref, path + datastr])
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 29: ordinal not in range(128)

bzr 2.7.0 on python 2.7.16 (Linux-5.1.11-arch1-1-ARCH-x86_64-with-glibc2.2.5)
arguments: ['/usr/bin/bzr', 'fast-export', '--no-plain', '.']
plugins: bash_completion[2.7.0], changelog_merge[2.7.0],
    fastimport[0.14.0dev], grep[2.7.0], launchpad[2.7.0],
    netrc_credential_store[2.7.0], news_merge[2.7.0], po_merge[2.7.0],
    weave_fmt[2.7.0]
encoding: 'utf-8', fsenc: 'UTF-8', lang: 'fi_FI.UTF-8'

*** 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.