helena@yuggoth:~$ software-properties-gtk
gpg: /tmp/tmpyvez7i/trustdb.gpg: trustdb created
Traceback (most recent call last):
  File "/usr/bin/software-properties-gtk", line 103, in <module>
    app = SoftwarePropertiesGtk(datadir=options.data_dir, options=options, file=file)
  File "/usr/lib/python3/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 173, in __init__
    self.show_distro()
  File "/usr/lib/python3/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 358, in show_distro
    self.block_handlers()
  File "/usr/lib/python3/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 348, in block_handlers
    if widget.handler_is_connected(self.handlers[widget]):
  File "/usr/lib/python3/dist-packages/gi/overrides/GObject.py", line 429, in wrapper
    return func(_get_instance_for_signal(obj), *args, **kwargs)
  File "/usr/lib/python3/dist-packages/gi/types.py", line 113, in function
    return info.invoke(*args, **kwargs)
TypeError: argument instance: Expected GObject.Object, but got PyCapsule