error: can't start new thread

[johannes]

* duplicity 0.7.16
* Python 2.7.14
* Arch
* Backup via ftp (remote systems identifies as UNIX)
* The error is reproducable, each time when running dejadup it happens at the 'verification' step

Traceback (innermost last):
  File "/bin/duplicity", line 1559, in <module>
    with_tempdir(main)
  File "/bin/duplicity", line 1545, in with_tempdir
    fn()
  File "/bin/duplicity", line 1394, in main
    do_backup(action)
  File "/bin/duplicity", line 1473, in do_backup
    restore(col_stats)
  File "/bin/duplicity", line 729, in restore
    restore_get_patched_rop_iter(col_stats)):
  File "/usr/lib/python2.7/site-packages/duplicity/patchdir.py", line 558, in Write_ROPaths
    for ropath in rop_iter:
  File "/usr/lib/python2.7/site-packages/duplicity/patchdir.py", line 521, in integrate_patch_iters
    for patch_seq in collated:
  File "/usr/lib/python2.7/site-packages/duplicity/patchdir.py", line 389, in yield_tuples
    setrorps(overflow, elems)
  File "/usr/lib/python2.7/site-packages/duplicity/patchdir.py", line 378, in setrorps
    elems[i] = iter_list[i].next()
  File "/usr/lib/python2.7/site-packages/duplicity/patchdir.py", line 107, in filter_path_iter
    for path in path_iter:
  File "/usr/lib/python2.7/site-packages/duplicity/patchdir.py", line 121, in difftar2path_iter
    tarinfo_list = [tar_iter.next()]
  File "/usr/lib/python2.7/site-packages/duplicity/patchdir.py", line 339, in next
    self.set_tarfile()
  File "/usr/lib/python2.7/site-packages/duplicity/patchdir.py", line 333, in set_tarfile
    self.current_fp = self.fileobj_iter.next()
  File "/bin/duplicity", line 766, in get_fileobj_iter
    manifest.volume_info_dict[vol_num])
  File "/bin/duplicity", line 809, in restore_get_enc_fileobj
    fileobj = tdp.filtered_open_with_delete("rb")
  File "/usr/lib/python2.7/site-packages/duplicity/dup_temp.py", line 120, in filtered_open_with_delete
    fh = FileobjHooked(path.DupPath.filtered_open(self, mode))
  File "/usr/lib/python2.7/site-packages/duplicity/path.py", line 779, in filtered_open
    return gpg.GPGFile(False, self, gpg_profile)
  File "/usr/lib/python2.7/site-packages/duplicity/gpg.py", line 224, in __init__
    'logger': self.logger_fp})
  File "/usr/lib/python2.7/site-packages/duplicity/gpginterface.py", line 374, in run
    create_fhs, attach_fhs)
  File "/usr/lib/python2.7/site-packages/duplicity/gpginterface.py", line 420, in _attach_fork_exec
    process.thread.start()
  File "/usr/lib/python2.7/threading.py", line 736, in start
    _start_new_thread(self.__bootstrap, ())
 error: can't start new thread