DiffDirException("Bad tarinfo name %s" % (tiname,)) (lp:#1674423)

[Original report](https://bugs.launchpad.net/bugs/1674423) created by **Fabio (fabiot2)**
```
Hi

unfortunately I'm getting this error on my Mac ( brew install duplicity ) :

Main action: list-current
================================================================================
duplicity 0.7.11 (December 31, 2016)
Args: /usr/local/bin/duplicity list-current-files --verbosity 5
sftp://USER@USER.your-
storagebox.de:/backups/cloud.terradue.int/data/cloud/one/datastores/1/2727f8942d3b99beabda9ef7148b07ae/2017-03-10_08:47
Darwin Fabios-MacBook-Pro.local 16.4.0 Darwin Kernel Version 16.4.0: Thu
Dec 22 22:53:21 PST 2016; root:xnu-3789.41.3~3/RELEASE_X86_64 x86_64 i386
/usr/local/Cellar/duplicity/0.7.11/libexec/bin/python 2.7.10 (default, Jul
30 2016, 19:40:32)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.34)]
================================================================================
Local and Remote metadata are synchronized, no sync needed.
Processing local manifest
/Users/martinelli_f/.cache/duplicity/8323b109d215f9e4e23b0928fd4f2a4e/duplicity-
full.20170310T074759Z.manifest (831)
Found 6 volumes in manifest
Last full backup date: Fri Mar 10 08:47:59 2017
Using temporary directory
/var/folders/ct/n230dw6n09d74yzwc3zp1j7w0000gn/T/duplicity-iBFZjG-tempdir
Traceback (most recent call last):
  File "/usr/local/bin/duplicity", line 1546, in <module>
    with_tempdir(main)
  File "/usr/local/bin/duplicity", line 1540, in with_tempdir
    fn()
  File "/usr/local/bin/duplicity", line 1391, in main
    do_backup(action)
  File "/usr/local/bin/duplicity", line 1472, in do_backup
    list_current(col_stats)
  File "/usr/local/bin/duplicity", line 707, in list_current
    for path in path_iter:
  File "/usr/local/Cellar/duplicity/0.7.11/libexec/lib/python2.7/site-
packages/duplicity/diffdir.py", line 350, in combine_path_iters
    triple_list = [x for x in map(get_triple, range(len(path_iter_list)))
if x]
  File "/usr/local/Cellar/duplicity/0.7.11/libexec/lib/python2.7/site-
packages/duplicity/diffdir.py", line 327, in get_triple
    path = path_iter_list[iter_index].next()
  File "/usr/local/Cellar/duplicity/0.7.11/libexec/lib/python2.7/site-
packages/duplicity/diffdir.py", line 247, in sigtar2path_iter
    raise DiffDirException("Bad tarinfo name %s" % (tiname,))
DiffDirException: Bad tarinfo name signature


despite of :
Main action: collection-status
================================================================================
duplicity 0.7.11 (December 31, 2016)
Args: /usr/local/bin/duplicity collection-status --verbosity 5
sftp://USER@USER.your-
storagebox.de:/backups/cloud.terradue.int/data/cloud/one/datastores/1/2727f8942d3b99beabda9ef7148b07ae/2017-03-10_08:47
Darwin Fabios-MacBook-Pro.local 16.4.0 Darwin Kernel Version 16.4.0: Thu
Dec 22 22:53:21 PST 2016; root:xnu-3789.41.3~3/RELEASE_X86_64 x86_64 i386
/usr/local/Cellar/duplicity/0.7.11/libexec/bin/python 2.7.10 (default, Jul
30 2016, 19:40:32)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.34)]
================================================================================
Local and Remote metadata are synchronized, no sync needed.
Processing local manifest
/Users/martinelli_f/.cache/duplicity/8323b109d215f9e4e23b0928fd4f2a4e/duplicity-
full.20170310T074759Z.manifest (831)
Found 6 volumes in manifest
Last full backup date: Fri Mar 10 08:47:59 2017
Collection Status
-----------------
Connecting with backend: BackendWrapper
Archive dir:
/Users/martinelli_f/.cache/duplicity/8323b109d215f9e4e23b0928fd4f2a4e

Found 0 secondary backup chains.

Found primary backup chain with matching signature chain:
-------------------------
Chain start time: Fri Mar 10 08:47:59 2017
Chain end time: Fri Mar 10 08:47:59 2017
Number of contained backup sets: 1
Total number of contained volumes: 6
 Type of backup set:                            Time:      Num volumes:
                Full         Fri Mar 10 08:47:59 2017                 6
-------------------------
No orphaned or incomplete backup sets found.
Using temporary directory
/var/folders/ct/n230dw6n09d74yzwc3zp1j7w0000gn/T/duplicity-secJnR-tempdir


kindly what may I check ?

thank you very much,
Fabio
```

Story points: 6.0