In [166]: with reversion.create_revision():
  for o in Res.objects.all():
    o.save()
   .....:

In [169]: Res.objects.all().delete()
In [170]: reversion.models.Revision.objects.all()
Out[170]: [<Revision: a>, <Revision: b>, <Revision: a>, <Revision: b>, <Revision: a>, <Revision: b>, <Revision: #00001>, <Revision: name: <bb>, desc: <bb>, doc: <bb>, group: <bb>-<bb>, #00002>]
In [174]: from django.contrib.contenttypes.models import ContentType

In [175]: r = reversion.models.Revision.objects.filter(content_type=ContentType.objects.get_for_model(Res)).order_by("-date_created")[0]
FieldError: Cannot resolve keyword 'content_type' into field. Choices are: comment, date_created, id, manager_slug, user, version


In [176]: r = reversion.models.Revision.objects.all().order_by("-date_created")[0]
In [177]: r
Out[177]: <Revision: name: <bb>, desc: <bb>, doc: <bb>, group: <bb>-<bb>, #00002>
In [179]: r.version_set.all()
Out[179]: [<Version: name: <bb>, desc: <bb>, doc: <bb>, group: <bb>-<bb>>, <Version: #00002>]