[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.

usr/bin/cubicweb-ctl usr/bin/
usr/lib/PY_VERSION/*-packages/cubicweb/cwctl.py
../cubicweb-ctl.bash_completion etc/bash_completion.d/cubicweb-ctl