[Duplicity-talk] 0.6.22: new_key on object-less URI

[svoop]

Since the upgrade to duplicity-0.6.22 (boto-2.11.0) I get an error
"InvalidUriError: new_key on object-less URI" when backing up with:

duplicity                                   \
  --full-if-older-than 1M                   \
  --encrypt-sign-key ########               \
  --include /backup                         \
  --include /etc                            \
  --exclude '**'                            \
  --exclude-other-filesystems               \
  /                                         \
  s3+http://tango.bitcetera.com             \
  --s3-european-buckets                     \
  --s3-use-new-style                        \
  --num-retries 3                           \
  --verbosity error

Here's the full error:

Traceback (most recent call last):
  File "/usr/bin/duplicity-python2.7", line 1466, in <module>
    with_tempdir(main)
  File "/usr/bin/duplicity-python2.7", line 1459, in with_tempdir
    fn()
  File "/usr/bin/duplicity-python2.7", line 1440, in main
    check_last_manifest(col_stats) # not needed for full backup
  File "/usr/bin/duplicity-python2.7", line 1160, in check_last_manifest
    last_backup_set.check_manifests()
  File "/usr/lib64/python2.7/site-packages/duplicity/collections.py", line
186, in check_manifests
    remote_manifest = self.get_remote_manifest()
  File "/usr/lib64/python2.7/site-packages/duplicity/collections.py", line
220, in get_remote_manifest
    manifest_buffer = self.backend.get_data(self.remote_manifest_name)
  File "/usr/lib64/python2.7/site-packages/duplicity/backend.py", line 631,
in get_data
    fin = self.get_fileobj_read(filename, parseresults)
  File "/usr/lib64/python2.7/site-packages/duplicity/backend.py", line 592,
in get_fileobj_read
    self.get(filename, tdp)
  File
"/usr/lib64/python2.7/site-packages/duplicity/backends/_boto_single.py",
line 242, in get
    key = self.storage_uri.new_key()
  File "/usr/lib64/python2.7/site-packages/boto/storage_uri.py", line 194,
in new_key
    self._check_object_uri('new_key')
  File "/usr/lib64/python2.7/site-packages/boto/storage_uri.py", line 84, in
_check_object_uri
    (function_name, self.uri))
InvalidUriError: new_key on object-less URI (s3://tango.bitcetera.com/)

I don't know Python at all, so I'm lost here. Thanks for your hints!