cubicweb-vcsfile #2731056 should detect new obsolescence from existing revisions [done]

when an obsolescence relation is added between two existing revisions, vcsfile correctly detects that one is hidden, but doesn't add the obsolescence relation to the db.

prioritynormal
typebug
done in1.12.1
load left0.000
closed by#fa2beef9351b [hook] detect obsolescence marker addition in some case (closes #2731056)