"bzr push" fails with vsftpd

bzr 0.18
Transport: FTP
Server: vsFTPd 2.0.3

I'm able to branch/checkout from a certain FTP server, but any write operation (push, init, merge, ...) to that FTP server fails with an error message like this:
bzr: ERROR: Generic path error: '/test/.bzr/repository/lock/72k47q9ysd.tmp/info': : unable to rename to u'/test/.bzr/repository/lock/72k47q9ysd.tmp/tmp.info.1185998528.367719889.13603.9k0x24hwtr': 550 RNFR command failed.)

Log:
FTP put: /test/.bzr/repository/lock/72k47q9ysd.tmp/info
unable to understand error for path: /test/.bzr/repository/lock/72k47q9ysd.tmp/info: 550 RNFR command failed.
Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 729, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 691, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 389, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.5/site-packages/bzrlib/builtins.py", line 791, in run
    push_result = br_from.push(br_to, overwrite)
  File "/usr/lib/python2.5/site-packages/bzrlib/decorators.py", line 127, in read_locked
    return unbound(self, *args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/branch.py", line 1544, in push
    target.lock_write()
  File "/usr/lib/python2.5/site-packages/bzrlib/branch.py", line 1320, in lock_write
    repo_token = self.repository.lock_write()
  File "/usr/lib/python2.5/site-packages/bzrlib/repository.py", line 252, in lock_write
    return self.control_files.lock_write(token=token)
  File "/usr/lib/python2.5/site-packages/bzrlib/lockable_files.py", line 258, in lock_write
    token_from_lock = self._lock.lock_write(token=token)
  File "/usr/lib/python2.5/site-packages/bzrlib/lockdir.py", line 556, in lock_write
    return self.wait_lock()
  File "/usr/lib/python2.5/site-packages/bzrlib/lockdir.py", line 485, in wait_lock
    return self.attempt_lock()
  File "/usr/lib/python2.5/site-packages/bzrlib/lockdir.py", line 451, in attempt_lock
    return self._attempt_lock()
  File "/usr/lib/python2.5/site-packages/bzrlib/lockdir.py", line 217, in _attempt_lock
    tmpname = self._create_pending_dir()
  File "/usr/lib/python2.5/site-packages/bzrlib/lockdir.py", line 277, in _create_pending_dir
    info_bytes)
  File "/usr/lib/python2.5/site-packages/bzrlib/transport/__init__.py", line 730, in put_bytes_non_atomic
    dir_mode=dir_mode)
  File "/usr/lib/python2.5/site-packages/bzrlib/transport/__init__.py", line 771, in put_file_non_atomic
    return self.put_file(relpath, f, mode=mode)
  File "/usr/lib/python2.5/site-packages/bzrlib/transport/ftp.py", line 323, in put_file
    self._rename_and_overwrite(tmp_abspath, abspath, f)
  File "/usr/lib/python2.5/site-packages/bzrlib/transport/ftp.py", line 477, in _rename_and_overwrite
    unlink_func=lambda p: self._delete(p, f))
  File "/usr/lib/python2.5/site-packages/bzrlib/osutils.py", line 205, in fancy_rename
    rename_func(new, tmp_name)
  File "/usr/lib/python2.5/site-packages/bzrlib/transport/ftp.py", line 476, in <lambda>
    rename_func=lambda p1, p2: self._rename(p1, p2, f),
  File "/usr/lib/python2.5/site-packages/bzrlib/transport/ftp.py", line 455, in _rename
    ': unable to rename to %r' % (abs_to))
  File "/usr/lib/python2.5/site-packages/bzrlib/transport/ftp.py", line 181, in _translate_perm_error
    raise unknown_exc(path, extra=extra)
FtpPathError: Generic path error: '/test/.bzr/repository/lock/72k47q9ysd.tmp/info': : unable to rename to u'/test/.bzr/repository/lock/72k47q9ysd.tmp/tmp.info.1185998528.367719889.13603.9k0x24hwtr': 550 RNFR command failed.)

return code 3

In order to see what's going on I monitored the connection with Wireshark. What happens is that bzr stores a file under a temporary name, then tries to rename the file using its final name (I suspect this is intended because of concurrency reasons) and finally fails to interpret the error message correctly:
C: STOR /test/.bzr/branch-lock/aptufh7qnq.tmp/info.tmp.1185994540.531426907.8842.385769306

S: 150 Ok to send data.

S: 226 File receive OK.

-------------------------------------------------------------------------------------------------
C: RNFR /test/.bzr/branch-lock/aptufh7qnq.tmp/info

S: 550 RNFR command failed.

On another FTP server, write operations work perfectly because that server returns a different error message for the first RNFR (ReName FRom) with the "wrong" file name:
C: STOR /bzr/test/.bzr/branch-lock/yif8vj7efe.tmp/info.tmp.1185995047.747515917.9064.1607528267

S: 150 Opening BINARY mode data connection for /bzr/test/.bzr/branch-lock/yif8vj7efe.tmp/info.tmp.1185995047.747515917.9064.1607528267

S: 226 Transfer complete.
-------------------------------------------------------------------------------------------------

C: RNFR /bzr/test/.bzr/branch-lock/yif8vj7efe.tmp/info

S: 550 /bzr/test/.bzr/branch-lock/yif8vj7efe.tmp/info: No such file or directory

-------------------------------------------------------------------------------------------------
C: RNFR /bzr/test/.bzr/branch-lock/yif8vj7efe.tmp/info.tmp.1185995047.747515917.9064.1607528267

S: 350 File or directory exists, ready for destination name.

C: RNTO /bzr/test/.bzr/branch-lock/yif8vj7efe.tmp/info

S: 250 Rename successful

C: RNFR /bzr/test/.bzr/branch-lock/yif8vj7efe.tmp

S: 350 File or directory exists, ready for destination name.

C: RNTO /bzr/test/.bzr/branch-lock/held

S: 250 Rename successful

As can be seen in the vsFTPd source code (ftp://vsftpd.beasts.org/users/cevans/untar/vsftpd-2.0.5/postlogin.c; lines 1206-1220), vsFTPd always returns "550 RNFR command failed." if a source file doesn't exist, so bzr should interpret this message as errors.NoSuchFile exception.