I've been testing out Go for a while now and outside of deployment, the CPU performance and GC tuning that has come with new versions has been a really, really great perk over time. No code change, no breakage, just constant free performance.
We can see the way Go solves this problem without breaking your code, a way not taken these days where not so well designed solutions break when we have to upgrade. Python 2 and python 3, angular 1 and angular 2. I guess this is the difference between a pet project gone wild and a well thought and well designed programming language designed to make the process of building applications faster and better!
Go is too young, and has extremely small adoption compared to Python, C, C++, Java. When a language has been around for so long that entire idioms have changed (functional in, object out, reactive in, iteration out etc.), the usage landscape has changed (from desktop scripts up to cloud-scale and down to mobile-app scale), it is natural for the language to have to adapt.
The hope is that Go will have enough adoption to require breaking changes!