[repo] normalize ValidationError on edited entity (closes #2509729)
In CubicWeb, ValidationError.entity MUST be the eid of the involved entity,
not the entity iteself (as done by yams).
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/index.html
Files: /usr/share/doc/cubicweb-documentation/*.html