Comment 2 for bug 1852876

Also affects me in Ubuntu 19.10. It prepares backup and while trying to store it gives this error

Traceback (innermost last):
  File "/usr/bin/duplicity", line 107, in <module>
    with_tempdir(main)
  File "/usr/bin/duplicity", line 93, in with_tempdir
    fn()
  File "/usr/lib/python3/dist-packages/duplicity/dup_main.py", line 1535, in main
    do_backup(action)
  File "/usr/lib/python3/dist-packages/duplicity/dup_main.py", line 1659, in do_backup
    full_backup(col_stats)
  File "/usr/lib/python3/dist-packages/duplicity/dup_main.py", line 565, in full_backup
    globals.backend)
  File "/usr/lib/python3/dist-packages/duplicity/dup_main.py", line 422, in write_multivol
    globals.volsize)
  File "/usr/lib/python3/dist-packages/duplicity/gpg.py", line 393, in GPGWriteFile
    data = block_iter.__next__().data
  File "/usr/lib/python3/dist-packages/duplicity/diffdir.py", line 542, in __next__
    result = self.process(next(self.input_iter)) # pylint: disable=assignment-from-no-return
  File "/usr/lib/python3/dist-packages/duplicity/diffdir.py", line 680, in process
    data, last_block = self.get_data_block(fp)
  File "/usr/lib/python3/dist-packages/duplicity/diffdir.py", line 707, in get_data_block
    buf = fp.read(read_size)
  File "/usr/lib/python3/dist-packages/duplicity/diffdir.py", line 449, in read
    buf = self.infile.read(length)
  File "/usr/lib/python3/dist-packages/duplicity/diffdir.py", line 417, in read
    log.Warn(_(u"Error %s getting delta for %s") % (str(ex), self.infile.uc_name))
 AttributeError: '_io.BufferedReader' object has no attribute 'uc_name'