I'm having the same bug/error:

[---@+++ ~]$ uname -a
Linux +++.*** 4.12.14-300.fc26.x86_64 #1 SMP Wed Sep 20 16:28:07 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

[---@+++ ~]$ dnf info deja-dup
Última verificação de expiração de metadados: 10 days, 2:25:23 em seg 18 set 2017 17:26:58 WEST.
Pacotes Instalados
Nome         : deja-dup
Versão       : 36.1
Lançamento   : 1.fc26
Arq.         : x86_64
Tamanho      : 4.0 M
Fonte        : deja-dup-36.1-1.fc26.src.rpm
Repositório  : @System
Do repositór : updates
Resumo       : Simple backup tool and frontend for duplicity
URL          : https://launchpad.net/deja-dup
Licença      : GPLv3+
Descrição    : Déjà Dup is a simple backup tool. It hides the complexity of
             : doing backups the 'right way' (encrypted, off-site, and regular)
             : and uses duplicity as the backend.
             : 
             : Features:
             :  • Support for local, remote, or cloud backup locations (Amazon
             : S3 or Rackspace) • Securely encrypts and compresses your data
             :  • Incrementally backs up, letting you restore from any
             : particular backup • Schedules regular backups
             :  • Integrates well into your GNOME desktop

[---@+++ ~]$ dnf info duplicity
Última verificação de expiração de metadados: 10 days, 2:26:58 em seg 18 set 2017 17:26:58 WEST.
Pacotes Instalados
Nome         : duplicity
Versão       : 0.7.13.1
Lançamento   : 2.fc26
Arq.         : x86_64
Tamanho      : 2.4 M
Fonte        : duplicity-0.7.13.1-2.fc26.src.rpm
Repositório  : @System
Do repositór : updates
Resumo       : Encrypted bandwidth-efficient backup using rsync algorithm
URL          : http://www.nongnu.org/duplicity/
Licença      : GPLv2+
Descrição    : Duplicity incrementally backs up files and directory by encrypting
             : tar-format volumes with GnuPG and uploading them to a remote (or
             : local) file server. In theory many protocols for connecting to a
             : file server could be supported; so far ssh/scp, local file access,
             : rsync, ftp, HSI, WebDAV and Amazon S3 have been written.
             : 
             : Because duplicity uses librsync, the incremental archives are space
             : efficient and only record the parts of files that have changed since
             : the last backup. Currently duplicity supports deleted files, full
             : unix permissions, directories, symbolic links, fifos, device files,
             : but not hard links.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Traceback (most recent call last):
  File "/usr/bin/duplicity", line 1540, in <module>
    with_tempdir(main)
  File "/usr/bin/duplicity", line 1534, in with_tempdir
    fn()
  File "/usr/bin/duplicity", line 1385, in main
    do_backup(action)
  File "/usr/bin/duplicity", line 1515, in do_backup
    check_last_manifest(col_stats)  # not needed for full backup
  File "/usr/bin/duplicity", line 1219, in check_last_manifest
    last_backup_set.check_manifests()
  File "/usr/lib64/python2.7/site-packages/duplicity/collections.py", line 199, in check_manifests
    remote_manifest = self.get_remote_manifest()
  File "/usr/lib64/python2.7/site-packages/duplicity/collections.py", line 234, 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 677, in get_data
    fin = self.get_fileobj_read(filename, parseresults)
  File "/usr/lib64/python2.7/site-packages/duplicity/backend.py", line 669, in get_fileobj_read
    self.get(filename, tdp)
  File "/usr/lib64/python2.7/site-packages/duplicity/backend.py", line 376, in inner_retry
    % exception_traceback())
  File "/usr/lib64/python2.7/site-packages/duplicity/util.py", line 51, in exception_traceback
    return uexc(msg)
  File "/usr/lib64/python2.7/site-packages/duplicity/util.py", line 79, in uexc
    e = unicode(e).encode('utf-8')
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 597: ordinal not in range(128)