Rollback of a document with an attachment to a prior version without this attachment does not rollback the attachment

When you want to rollback to a previous of a document that has a different set of attachment content then the attachment content is not rollback.
This can create an instable state since the attachment list could not list attachments that are still in the database.

One way to fix it is to rollback attachments to the prior versions or delete them if they are not in the list anymore.

However this has a problem because you can't rollback deletions of attachments since the attachments are not there anymore.
This relates to bug XWIKI-850