Fix default DOI when adding content

[reinhardt]

This is probably not a final fix but it does fix an error when calling dexterity-types/*/@@fields on a type that uses the IBaseReview behavior.

syslabcom/scrum#1199

[thet]

I have a suggestion, which IMO should be implemented. If you do, just merge it then - you've got my approval.
If you decide against then there are reasons for that and then also go ahead and merge :)

[thet]

I think it would be nicer, maybe also more performant‌ (which probably isn't a problem here) if you would use a marker interface.

You create a marker interface, register it for the behavior like so:

  <plone:behavior
      name="recensio.base_review"
      title="Base Review Behavior"
      factory=".base_review.BaseReview"
      provides=".base_review.IBaseReview"
      marker=".base_review.IBaseReviewMarker"
      for="plone.dexterity.interfaces.IDexterityContent"
      />

and then:

Suggested change

	if IBaseReview not in iterSchemata(context):
	if not IBaseReviewMarker.providedBy(context):

[reinhardt]

It's a good suggestion but a bad time to implement it because it's not yet clear whether the whole DOI generation/registration code is going to stay or be removed or reworked. So I'll merge as-is for a quick fix, and we'll likely revisit it later and can then decide about the marker interface. Cheers!