So this is kind of convoluted. With an input like

    Relearn::Can it scale to the universe

    we get a pad, with the unchangeable id:

    relearn::can-it-scale-to-the-universe

    This id becomes the initial value for the (changeable) url slug, as display_slug.
    Based on this id we also set the (changeable) display name, as display_name,
    through a slight transformation (- becomes space, :: →) as in:

    relearn → can it scale to the universe

After migration, update existing install as such:

from etherpadlite.models import Pad
from relearn.templatetags.wikify import dewikify

for pad in Pad.objects.all():
    pad.display_slug = pad.name
    pad.display_name = dewikify(pad.name)
    pad.save()