unicode errors in sigtar2path_iter on filenames with non ascii characters

[Bas Hulsken]

when encountering files with non ascii (latin-1 special chars such as u umlaut, etc.) duplicity breaks with the following error:

--- Start running command BKP at 20:51:28.814 ---
Traceback (innermost last):
  File "/usr/bin/duplicity", line 1668, in <module>
    with_tempdir(main)
  File "/usr/bin/duplicity", line 1654, in with_tempdir
    fn()
  File "/usr/bin/duplicity", line 1501, in main
    do_backup(action)
  File "/usr/bin/duplicity", line 1636, in do_backup
    incremental_backup(sig_chain)
  File "/usr/bin/duplicity", line 658, in incremental_backup
    globals.backend)
  File "/usr/bin/duplicity", line 419, in write_multivol
    globals.volsize)
  File "/usr/lib64/python2.7/site-packages/duplicity/gpg.py", line 386, in GPGWriteFile
    data = block_iter.next().data
  File "/usr/lib64/python2.7/site-packages/duplicity/diffdir.py", line 523, in next
    result = self.process(next(self.input_iter))
  File "/usr/lib64/python2.7/site-packages/duplicity/diffdir.py", line 195, in get_delta_iter
    for new_path, sig_path in collated:
  File "/usr/lib64/python2.7/site-packages/duplicity/diffdir.py", line 286, in collate2iters
    relem2 = next(riter2)
  File "/usr/lib64/python2.7/site-packages/duplicity/diffdir.py", line 354, in combine_path_iters
    refresh_triple_list(triple_list)
  File "/usr/lib64/python2.7/site-packages/duplicity/diffdir.py", line 341, in refresh_triple_list
    new_triple = get_triple(old_triple[1])
  File "/usr/lib64/python2.7/site-packages/duplicity/diffdir.py", line 327, in get_triple
    path = next(path_iter_list[iter_index])
  File "/usr/lib64/python2.7/site-packages/duplicity/diffdir.py", line 249, in sigtar2path_iter
    index = tuple(name.split(u"/"))
 UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 54: ordinal not in range(128)

20:53:06.906 Task 'BKP' failed with exit code '30'.
--- Finished state FAILED 'code 30' at 20:53:06.906 - Runtime 00:01:38.091 ---

the filename it chokes on is this one:
/var/www/html/lustband/03 - Lustband - Wat zou je doen_ (Bløf).mp3

problem seems unicode split to tokenize a string that was treated as a bytestring before.

patch below fixes this for me, and seems in line with the intent of the code, but I haven't spend a lot of time understanding the (unicode) filename handling in duplicity, so I might be wrong.

some version info:
Start duply v2.1, time is 2018-10-14 20:51:28.
Using profile '/etc/duply/dirvish-steady-var'.
Using installed duplicity version 0.8.00, python 2.7.15 (/usr/bin/python2), gpg 1.4.22 (Home: ~/.gnupg), awk 'GNU Awk 4.1.4, API: 1.1 (GNU MPFR 3.1.6-p2, GNU MP 6.1.2)', grep 'grep (GNU grep) 3.1', bash '4.4.12(1)-release (x86_64-redhat-linux-gnu)'.

best regards,
Bas Hulsken

diff -Naupr duplicity/duplicity/diffdir.py duplicity-fix/duplicity/diffdir.py
--- duplicity/duplicity/diffdir.py 2018-10-06 15:26:27.358130000 +0200
+++ duplicity-fix/duplicity/diffdir.py 2018-10-14 20:34:53.830534389 +0200
@@ -246,7 +246,7 @@ def sigtar2path_iter(sigtarobj):
         else:
             raise DiffDirException(u"Bad tarinfo name %s" % (tiname,))

- index = tuple(name.split(u"/"))
+ index = tuple(name.split(b"/"))
         if not index[-1]:
             index = index[:-1] # deal with trailing /, ""