The COPYING file at the top level of the source tree contains the GPLv2.  The about box in src/dfeet/application.py contains:

  self.set_license_type(Gtk.License.GPL_2_0)

However, the file src/dfeet/window.py contains the following:

  # D-Feet is free software: you can redistribute it and/or modify
  # it under the terms of the GNU General Public License as published by
  # the Free Software Foundation, either version 3 of the License, or
  # (at your option) any later version.

Some parts of the source code contain GPLv2 notices, some parts contains GPLv3 notices.  Plainly this is an issue and I would expect legally problematic.

In addition, the following files under src/dfeet/ contain no copyright or licensing notices at all: addconnectiondialog.py, application.py, bus_watch.py, dbus_utils.py, executemethoddialog.py, introspection.py, introspection_helper.py, uiloader.py and wnck_utils.py.  The file settings.py contains no copyright notice and incomplete license information.