So why is the defacto vendoring system for the Go tooling incompatible with old Go versions (the "organic" solutions were compatible with Go versions without vendoring support because they were implemented before vendoring support was a thing!)?
The vendor/src hack meant that you could compile with ANY version of Go -- that's important for distributions (and other people who want to build runC and Docker -- put plainly we pin Go versions because of compiler bugs). But no, now we have to use vendor/ which means that now we have to do even more messing around with the GOPATH (which makes rpmbuild even more ugly than it needs to be). sigh