How to update a Django field which uses pre_save, within a pre_save hook?

[Zsolt Ero]

I am using Django Markitup to store markdown rendered versions of TextFields in a database. I'd like to normalise all unicode data upon save using unicodedata.normalize.

I've written a pre_save signal hook, which does this on all TextFields and CharField and it works well.

@receiver(pre_save)
def unicode_normalise(sender, **kwargs):
    obj = kwargs['instance']
    fields = obj._meta.fields
    for f in fields:
        # excluding django markitup rendered fields
        if f.name.endswith('_rendered'):
            continue

        if isinstance(f, MarkupField):
            _markupfield = getattr(obj, f.name)
            _markupfield.raw = normalize('NFC', getattr(obj, _markupfield.raw))
            # would need to re-render and save rendered version here

        elif isinstance(f, (models.CharField, models.TextField)):
            normalized = normalize('NFC', getattr(obj, f.name))
            setattr(obj, f.name, normalized)

But Django Markitup make things complicated, as it has this two field (raw, rendered) concept, which uses pre_save to render and save into it's hidden rendered field: GitHub source

My problem is that a field's pre_save has priority over the signal pre_save, so I cannot update the fields within the signal's pre_save function (comment inserted in code block above).

How can I re-run a field's pre_save function within my pre_save hook and make sure that the rendered markupfield is updated with the new version?