release stage: Panic instead of returning an error
release stage: Panic instead of returning an error

This is the standard way how to handle cancel in SalsaFlow.
Not using prompt.PanicCancel leads to weird error messages.

Change-Id: 57ce721ca4
Story-Id: salsaflow/salsaflow#110

salsaflow/salsaflow,salsaflow/salsaflow