I am glad there is now support for vendor directories, albeit experimental at this stage.

https://go-review.googlesource.com/#/c/10923/

Go 1.5 vendor proposal:

If there is a source directory d/vendor, then, when compiling a source file within the subtree rooted at d, import "p" is interpreted as import "d/vendor/p" if that exists.

When there are multiple possible resolutions, the most specific (longest) path wins.

The short form must always be used: no import path can contain “/vendor/” explicitly.

Import comments are ignored in vendored packages.