I just downloaded Go 1.7 for Apple OS from here. The package downloaded successfully as go1.7.darwin-amd64.pkg. I deleted my /usr/local/go and /etc/paths.d/go directories as per the standard upgrade instructions, then ran the downloaded package successfully. The install ran fine, and all files in /usr/local/go are dated 8/15/16 3:55PM.
However: Running go version returns: go version go1.6 darwin/amd64.
Running which go returns: /usr/local/bin/go, which is linked to: ../Cellar/go/1.6/bin/go.
I'm on MacOS 10.11.6 (15G31). I've had Cellar interfere with other upgrades and installs... what is the deal with Cellar?? Does the Go package installer need to know to flush the "Cellar" pre-existing contents, and relink /usr/local/bin/go? How do I best clean this up - just delete the Cellar contents and relink /usr/local/bin/go to /usr/local/go/bin/go? My $PATH is pointing to /usr/local/go/bin, but has /usr/local/bin ahead of it.
brew update && brew upgrade go
I had a similar problem and this command, as per squiguy's comment, solved it for me.