Reports whether a pipeline exists and could be prepared for a run.
Preparation needs no previous instance, so this answers before a caller
commits to anything — which matters when the commitment is a feed that would
otherwise be left behind when the run fails.
Reports whether a pipeline exists and could be prepared for a run.
Preparation needs no previous instance, so this answers before a caller commits to anything — which matters when the commitment is a feed that would otherwise be left behind when the run fails.