message: do not open file without closing!
  Not needed to open, because the buffer is only staged and no file changes are needed
diff: @@ -512,10 +512,6 @@ void FileWidget::stageHunks()
  QByteArray fileContent = dev.readAll();
  dev.close();
  - QSaveFile file(repo.workdir().filePath(name));
  - if (!file.open(QFile::WriteOnly))
  - return;
  -
  QByteArray buffer;
  QList<QList<QByteArray>> image;
  mPatch.populatePreimage(image, fileContent);
  