Allows versioning of the Plone Site type for the portal working copy to work

[wesleybl]

This is part of: plone/volto#5284

For the working copy of plone.app.iterate to work on the Plone Site type, it is necessary that this type is versionable. See:

https://github.com/plone/plone.app.iterate/blob/1908aa1f4e9c95c37143fae88655469b72ea451a/plone/app/iterate/browser/control.py#L88-L90

This also allows the "Plone Site" type to be cloned.

Products.CMFEditions uses the pickle module to clone objects. See:

Products.CMFEditions/Products/CMFEditions/ArchivistTool.py

Lines 210 to 229 in c80bc31

	def _cloneByPickle(self, obj):
	"""Returns a deep copy of a ZODB object, loading ghosts as needed."""
	modifier = getToolByName(self, "portal_modifier")
	callbacks = modifier.getOnCloneModifiers(obj)
	if callbacks is not None:
	pers_id, pers_load, inside_orefs, outside_orefs = callbacks[0:4]
	else:
	inside_orefs, outside_orefs = (), ()
	stream = BytesIO()
	p = Pickler(stream, 1)
	if callbacks is not None:
	p.persistent_id = pers_id
	p.dump(aq_base(obj))
	approxSize = stream.tell()
	stream.seek(0)
	u = Unpickler(stream)
	if callbacks is not None:
	u.persistent_load = pers_load
	return approxSize, u.load(), inside_orefs, outside_orefs

These changes prevent the error:

TypeError: Can't pickle objects in acquisition wrappers

When trying to serialize an ImplicitAcquisitionWrapper object with the pickle dump. This error occurred when trying to check in a Plone Site type with plone.app.iterate.

These changes also allow the Plone Site type to be serialized with the pickle. When the persistent_id method of SkipParentPointers returns something other than None, the object is not serialized. So we need to make sure it returns None for the Plone Site type.

[mister-roboto]

@wesleybl thanks for creating this Pull Request and helping to improve Plone!

TL;DR: Finish pushing changes, pass all other checks, then paste a comment:

@jenkins-plone-org please run jobs

To ensure that these changes do not break other parts of Plone, the Plone test suite matrix needs to pass, but it takes 30-60 min. Other CI checks are usually much faster and the Plone Jenkins resources are limited, so when done pushing changes and all other checks pass either start all Jenkins PR jobs yourself, or simply add the comment above in this PR to start all the jobs automatically.

Happy hacking!

[wesleybl]

@jenkins-plone-org please run jobs

[wesleybl]

I ran the tests for this PR along with plone/plone.app.iterate#128

See: Plone Jenkins CI - pull-request-6.0-3.11 and Plone Jenkins CI - pull-request-6.0-3.8

[wesleybl]

I'm not sure whether I should do an upgrade step for this or just leave it for new portals.