title: how to version packages in golang?
body: <p>I've read a whole bunch of articles and SO questions on importing 3rd party go packages which all seems straight forward, but what I don't understand is that none that I have read make any references to versioning. In Dartlang there's the pubspec file that defines your package including its version and its dependencies including their required versions. What if I do a <code>go get github.com/gorilla/sessions</code> and write my app then 6 months later I have to clear my directories and re get everything again, in which time that package has been update and broken backwards compatibility with my code that was using the older version?</p>