Everytime a new version of some content is published, a record is inserted in eznode_assignment table.
On these records from_node_id field has the value -1.
So far no consequences (besides the usage of data storage) have been identified.

Steps to reproduce:

• create an article
• run select * from eznode_assignment where contentobject_id=<article-object-id>
• create and publish a new version of the article
• rerun the the query and notice the new record