[form controller] clear caches in case some attribute participating to the rest path has been modified, avoid redirection to a no more existant page (fix #753567)
"""pre 3.6 bw compat"""# pylint: disable-msg=W0614,W0401fromwarningsimportwarnwarn('moved to cubicweb.mttransforms',DeprecationWarning,stacklevel=2)fromcubicweb.mttransformsimport*