> (pro tip: never happened)

It won't work today, but was this really so improbable in the past? There was a time when jQuery was so ubiquitous to be almost a "de-facto standard" at it also had a "canonical url" to load from (per version at least). Why would it have been so improbable that a user visited two or more sites that used the same jQuery version and also included it from the canonical url?