One of Google's core Go developers addressed this "master" problem at a golang conference some time ago. He said Go developers are expected to keep master clean. Maybe that works inside Google, where employees must adopt the policies of their employer. For the rest of the world this has been a terrible policy; whatever time one is supposed to have saved with simple abstractions and fast compilers is utterly pissed away herding dependencies and fixing breakage due to changing masters.
Builds must be easily reproducible, and that requires enumerated, versioned dependencies. The fact that this appears to be lost on The Powers That Be behind Go is astonishing. I seriously studied Go; read the book end to end and drank all the necessary kool-aid. Then I tried to use it for something. Two weeks after starting to work on toy projects to evaluate the language I walked away. The experience of trying to wade through the mess that accrues when trying to leverage libraries still makes me nauseous. I can't imagine trying to explain / apologize for Go dependency management to a peer. Complete non-starter.