There seems to be an issue installing Workflow Manager 1.0 refresh on Windows Server 2012 R2. Upon completion, when clicking through to configure Workflow Manager, you are informed that neither Service Bus 1.0, nor (obviously) CU1 for Service Bus 1.0 has been installed.
Digging into the event log on the machine in question, this shows that VC Redist 11.0 or greater is required, and this is not installed automatically by the WebPI.
On Windows Server 2012, VC redist 12.0 is installed automatically by WebPI and the installation of Workflow Manager 1.0 Refresh completes successfully.
Obviously the solution is to install VC redist 11.0 or 12.0 before attempting to install Workflow Manager 1.0 refresh on Windows Server 2012 R2.