Restack does not work

On xubuntu-18.04-desktop-amd64.iso using Inkscape-beb7fdf-x86_64.AppImage

Running

Extensions > Arrange > Restack... > Apply

with nothing selected results in

Traceback (most recent call last):
  File "restack.py", line 199, in <module>
    Restack().run()
  File "/tmp/.mount_InkscahBdORb/usr/share/inkscape/extensions/inkex/base.py", line 84, in run
    ret = self.effect()
  File "restack.py", line 75, in effect
    inkex.errormsg(_("There is no selection to restack."))
NameError: global name '_' is not defined

With something selected I get:

restack.py:86: DeprecationWarning: Effect.selected is now a dictionary in the svg document. Use self.svg.selected instead.
  firstobject = self.selected[self.options.ids[0]]
restack.py:87: DeprecationWarning: Effect.selected is now a dictionary in the svg document. Use self.svg.selected instead.
  if len(self.selected) == 1 and firstobject.tag == inkex.addNS('g', 'svg'):
restack.py:92: DeprecationWarning: Effect.current_layer is now a method in the svg document. Use `self.svg.get_current_layer()` instead.
  parentnode = self.current_layer
restack.py:93: DeprecationWarning: Effect.selected is now a dictionary in the svg document. Use self.svg.selected instead.
  objects = self.selected

Please note: I only tested this on the system described above; I cannot guarantee that the same error exists in non-AppImage versions. Please let me know if it does not, so that we can iron out any remaining issues concerning bundling a private copy of Python inside the AppImage.