Oculus Utilities for Unity 1.18.1 screaming about OVR Plugin version after plugin upgrade

When I use Oculus Utilites for Unity version 1.18.1 it screams about the OVR Plugin version AFTER I let it upgrade the OVR Plugin and restart Unity, and I see conflicting stories about what the OVR Plugin version is.

Steps to reproduce:

* Get a computer running OS X/MacOS 10.12.6 (other versions may also reproduce)
* Get Unity 5.6.2f1 installed (other versions may also reproduce)
* Create a new project
* Download Oculus Utilites for Unity 1.18.1
* Unzip, and import...
* ... saying yes to upgrading OVR Plugin...
* and restarting Unity.
* Delete Main Camera and throw an OVRCameraRig in the scene
* Click play
* Observe versions printed in console:

    Unity v5.6.2f1, Oculus Utilities v1.18.1, OVRPlugin v1.14.1, SDK v0.0.0.

* Observe firehose of spam in console:

    ovrp_GetAppHasInputFocus only available on 1.18 and newer plugins
    UnityEngine.Debug:LogWarning(Object)
    OVRPlugin:get_hasInputFocus() (at Assets/OVR/Scripts/OVRPlugin.cs:964)
    OVRManager:Update() (at Assets/OVR/Scripts/OVRManager.cs:1089)

* Click stop
* Tools -> Oculus -> Update OVR Utilities Plugin
* Observe dialog claiming "Current version: 1.18.1" and no upgrade possible

* Expected behaviour:
    * No spam firehose
    * The following versions reported in the console

        Unity v5.6.2f1, Oculus Utilities v1.18.1, OVRPlugin v1.18.1, SDK v0.0.0.

* Tools -> Oculus -> Disable OVR Utilites Plugin
* Restart Unity
* Click play
* Observe the reported OVRPlugin version is now lower

    Unity v5.6.2f1, Oculus Utilities v1.18.1, OVRPlugin v1.14.0, SDK v0.0.0.

Previous thread on the subject where it is assumed that the OP didn't want to upgrade OVR Plugin even though they mention taking steps to ensure old versions didn't remain. Hopefully the reproduction steps in this thread will avoid a repeat.