How can you upgrade Go version to 1.2.1 on Nitrous.io? Default version on a Go box is 1.1.1.
Update it via the package manager, Autoparts: http://help.nitrous.io/autoparts/
I believe Go 1.2.1 is available in the repository: https://github.com/nitrous-io/autoparts/blob/master/lib/autoparts/packages/go.rb#L8
The command is:
parts install go