Updated openstack/openstack
Project: openstack/taskflow  a17a546896d3a5747dd9dfb9ad63cbc29568442c

Increase usefulness of the retry component compile errors

Adjust the descriptiveness of the errors raised when a
retry atom is used in a flow or as the root item of a
to help users understand why the error is raised.

Change-Id: Ia3e13382d49e2225d48b2ae875061f92c211093c