Forum Linux.debian/ubuntu rdiff-backup sur sparc

bonjour,
j'ai installé rdiff-backup sur une machine ultra sparc 5, debian sarge.
ma version de python est la 2.4.4.
voici ce qu'il se passe quand je lance rdiff-backup :

$rdiff-backup /home/gart/Maildir /mnt/backup/backup/gart 

Exception 'local variable 'ext_rp' referenced before assignment' raised of class 'exceptions.UnboundLocalError':

  File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 295, in error_check_Main

    try: Main(arglist)

  File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 315, in Main

    take_action(rps)

  File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 271, in take_action

    elif action == "backup": Backup(rps[0], rps[1])

  File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 325, in Backup

    rpout.conn.fs_abilities.backup_set_globals(rpin)

  File "/var/lib/python-support/python2.4/rdiff_backup/fs_abilities.py", line 602, in backup_set_globals

    dest_fsa = FSAbilities('destination').init_readwrite(Globals.rbdir)

  File "/var/lib/python-support/python2.4/rdiff_backup/fs_abilities.py", line 137, in init_readwrite

    self.set_extended_filenames(subdir)

  File "/var/lib/python-support/python2.4/rdiff_backup/fs_abilities.py", line 208, in set_extended_filenames

    assert not ext_rp.lstat()



Traceback (most recent call last):

  File "/usr/bin/rdiff-backup", line 23, in ?

    rdiff_backup.Main.error_check_Main(sys.argv[1:])

  File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 295, in error_check_Main

    try: Main(arglist)

  File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 315, in Main

    take_action(rps)

  File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 271, in take_action

    elif action == "backup": Backup(rps[0], rps[1])

  File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 325, in Backup

    rpout.conn.fs_abilities.backup_set_globals(rpin)

  File "/var/lib/python-support/python2.4/rdiff_backup/fs_abilities.py", line 602, in backup_set_globals

    dest_fsa = FSAbilities('destination').init_readwrite(Globals.rbdir)

  File "/var/lib/python-support/python2.4/rdiff_backup/fs_abilities.py", line 137, in init_readwrite

    self.set_extended_filenames(subdir)

  File "/var/lib/python-support/python2.4/rdiff_backup/fs_abilities.py", line 208, in set_extended_filenames

    assert not ext_rp.lstat()

UnboundLocalError: local variable 'ext_rp' referenced before assignment

j'ai cherché sur la mailing list "rdiff-backup users", mais rien ne se rapportant au problème.
Des idées ?