TODO: Handle dir_entry.stat() errors.

[jedie]

e.g.:

Traceback (most recent call last):
  File "/home/jens/PyHardLinkBackup/src/PyHardLinkBackup/PyHardLinkBackup/phlb/phlb_main.py", line 670, in backup
    phlb.backup()
  File "/home/jens/PyHardLinkBackup/src/PyHardLinkBackup/PyHardLinkBackup/phlb/phlb_main.py", line 339, in backup
    self._backup()
  File "/home/jens/PyHardLinkBackup/src/PyHardLinkBackup/PyHardLinkBackup/phlb/phlb_main.py", line 531, in _backup
    dir_entries = self._scandir(self.path_helper.abs_src_root)
  File "/home/jens/PyHardLinkBackup/src/PyHardLinkBackup/PyHardLinkBackup/phlb/phlb_main.py", line 390, in _scandir
    for entry in tqdm_iterator:
  File "/home/jens/PyHardLinkBackup/lib/python3.4/site-packages/tqdm/_tqdm.py", line 596, in __iter__
    for obj in iterable:
  File "/home/jens/PyHardLinkBackup/src/PyHardLinkBackup/PyHardLinkBackup/phlb/filesystem_walk.py", line 106, in iter_filtered_dir_entry
    dir_entry_path = DirEntryPath(entry)
  File "/home/jens/PyHardLinkBackup/lib/python3.4/site-packages/pathlib_revised/dir_entry_path.py", line 53, in __init__
    self.stat = dir_entry.stat(follow_symlinks=False)
  File "/home/jens/PyHardLinkBackup/lib/python3.4/site-packages/scandir.py", line 480, in stat
    self._lstat = lstat(self.path)
FileNotFoundError: [Errno 2] No such file or directory: '/foo/.~lock.bar.ods#'