Using the JSON RestAPI, I need to do things slightly differently depending on the version of Magento due to as-yet un-fixed bugs (specifically https://github.com/magento/magento2/issues/18005).
I can find the major and minor version numbers here
but that doesn't have the build number, and could (should) be disabled in production.
As I currently use the JSON API, I was hoping for something there already, but can't see anything.
(I acknowledge I could build a custom API endpoint, but at present that's a little out of my knowledge after scanning some articles that explain how it all works, plus I might not be able to install that on all the Magento sites I will integrate with.)
So, my question is, with legitimate API access, how can I determine the version of a Magento installation?