code: func decodeRefs(input string) (*git.Ref, *git.Ref) {
  	refs := strings.Split(strings.TrimSpace(input), " ")
  	for len(refs) < 4 {
  		refs = append(refs, "")
  	}
  
  	leftRef := git.ParseRef(refs[0], refs[1])
  	rightRef := git.ParseRef(refs[2], refs[3])
  	return leftRef, rightRef
  }
docs: // decodeRefs pulls the sha1s out of the line read from the pre-push
  // hook's stdin.