[storage/bfss] ensure bfss never remove a cw_edited item (closes #2236287)
When the <old value> == <new value> (not really and update but can happen), the
value was popped but never restored. The cw_edited attribut had wrong content
for a small time lapse.
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