[views/workflow/tmppng] fix console crash on nth call to this one-shot view The underlying design issue is not addressed here, only a cosmetic and "we understand and document what's happening" note. Related to #3400448.

usr/lib/PY_VERSION/*-packages/cubicweb/web
usr/share/cubicweb/cubes/shared/data
usr/share/cubicweb/cubes/shared/wdoc