So, why not:

  mkdir $GOPATH/src/mystuff

  git clone https://github.com/foo/bar 
  # may be switch to a branch here while you're at it

  mv bar $GOPATH/src/mystuff/bar

Now in your Go program

  import "mystuff/bar"

The whole "URL import" is not a "feature of Go", it's an artifact of "go get", just a tool to make it easier to pull code from github or whatever.