// lookupTip looks up the object referenced by refname, and returns it
// as a Commit object. If the reference does not exist, or if object is
// not a commit, nil is returned. Other errors cannot be detected.
func lookupTip(r *git.Repository, refname string) *git.Commit {
ref, err := r.LookupReference(refname)
if err != nil {
return nil
}
commit, err := lookupCommit(r, ref.Target())
if err != nil {
return nil
}
return commit
}
