[entity/url publishing] fetch_rqlst should use 'is_instance_of' instead of 'is'
We usually want to get any subclasses as well (think Training subclass of
Workcase). Closes #3210365.
usr/lib/PY_VERSION/*-packages/cubicweb/server/
usr/lib/PY_VERSION/*-packages/cubicweb/hooks/
usr/lib/PY_VERSION/*-packages/cubicweb/sobjects/
usr/lib/PY_VERSION/*-packages/cubicweb/schemas/
usr/share/cubicweb/migration/