FilePrefixError on all --exclude

[Jay Bienvenu]

I'm getting this error for the --exclude option, no matter what I specify to exclude and even if I --exclude-filelist. Here's an example of my trace. I'm using duplicity 0.7.17, Ubuntu 18.04.3 LTS, Python 2.7.15+.

> duplicity --exclude .git ~/source_folder file:///target
Traceback (innermost last):
  File "/usr/bin/duplicity", line 1555, in <module>
    with_tempdir(main)
  File "/usr/bin/duplicity", line 1541, in with_tempdir
    fn()
  File "/usr/bin/duplicity", line 1380, in main
    action = commandline.ProcessCommandLine(sys.argv[1:])
  File "/usr/lib/python2.7/dist-packages/duplicity/commandline.py", line 1149, in ProcessCommandLine
    set_selection()
  File "/usr/lib/python2.7/dist-packages/duplicity/commandline.py", line 973, in set_selection
    sel.ParseArgs(select_opts, select_files)
  File "/usr/lib/python2.7/dist-packages/duplicity/selection.py", line 250, in ParseArgs
    self.add_selection_func(self.glob_get_sf(arg, 0))
  File "/usr/lib/python2.7/dist-packages/duplicity/selection.py", line 434, in glob_get_sf
    sel_func = self.glob_get_filename_sf(glob_str, include)
  File "/usr/lib/python2.7/dist-packages/duplicity/selection.py", line 502, in glob_get_filename_sf
    raise FilePrefixError(filename)
 FilePrefixError: .git

> duplicity -v9
Command line error: Expected 2 args, got 0
Enter 'duplicity --help' for help screen.
Using temporary directory /tmp/duplicity-oupQbS-tempdir

[Matthijs Kooijman (matthijskooijman)]

This error means that the source you're backing up (`~/source_folder` is not a prefix of your exclude `.git`). Really that means that excludes should always match the full path, not just a single component. If you want to exclude all files/directories called .git, you could instead specify `--exclude **/.git` to specify all filenames where the last part is `.git`.