message: use first parent in the logs if available, otherwise nothing
diff: @@ -2165,7 +2165,10 @@ void RepoView::amend(const git::Commit &commit, const git::Signature &author,
  Q_ASSERT(head.isValid());
  QString title = tr("Amend");
  - QString text = tr("%1 to %2").arg(head.name(), commit.link());
  + QString text =
  + tr("%1%2").arg(head.name(), commit.parents().count() > 0
  + ? " on " + commit.parents().first().link()
  + : "");
  LogEntry *entry = addLogEntry(text, title);
  if (!mRepo.amend(commit, author, committer, commitMessage))
  