[web/test] don't depend on iteration order on a set
Fixes test under python -R ('pending_insert' in session data is a set,
so we can't rely on any particular ordering). Related to #4959402.
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