I interpret this as encouragement to use fully-qualified package names (eg: https://github.com/burke/zeus/blob/master/go/zeusmaster/zeus...), which I don't really have a problem with.
Go code is nothing if not explicit.
Go code is nothing if not explicit.
For a company, it makes sense to check your GOPATH into your own source control system, so everyone has the same version of the open source libraries you're using. Then upgrading some open source libraries to a new version is a commit like any other change.
I haven't messed with Go, but nothing about the idea of defining a path for source modules sounds braindead on its face to me. I certainly would give the benefit of any doubt to the designers of Go over some random troll.
How is that different than the /I ${INCLUDE} path of C/C++ compilers (and many other languages)?