UnicodeDecodeError with "bzr fast-import"

[Teemu Likonen]

I'm trying to fast-import two smallish git repositories to bzr.
Unfortunately I'm facing character encoding problems which I'm not able
to solve. I'm using the latest development revisions of both bzr and bzr
fast-import plugin.

The other repo does not convert at all. It stops almost immediately and
displays the following error:

  bzr: ERROR: exceptions.UnicodeDecodeError: 'ascii' codec can't decode
  byte 0xc3 in position 5: ordinal not in range(128)

The other repo converts nicely but in bzr commit messages individual
bytes in UTF-8 multibyte sequenced are converted to separate characters.
I.e. "ä" which is UTF-8 encoded as c3a4 (hex) will display as "ä" in
bzr log output.

Any ideas how to solve this?