With the installation and upgrade of LR managed by the CC installer, there's no exposure to being able to pick a specific version of LR to use. Additionally, from the CC installer, my recollection is that the install for LR is simply "Upgrade", whereas for PS there's "Update" (install latest patch) or "Install" (New version). For Bridge there was an option to also keep the current version, but I don't recall that for LR.
In the event that a LR upgrade does introduce problems and you want to go back, how does one do that? The installer doesn't let you pick any version and there's no URLs to get specific versions either.
Help?
(The reason for this is the problems with panorama merges observed in
https://forum.luminous-landscape.com/index.php?topic=137953.msg1227496#msg1227496.