After searching a lot I ask this.
I want to download the app source code from this url: https://android.googlesource.com/platform/packages/apps/Gallery2/+/ics-mr1
git clone https://android.googlesource.com/platform/packages/apps/Gallery2/+/ics-mr1 does not work.
git clone https://android.googlesource.com/platform/packages/apps/Gallery2/ works just fine.
What should I do to download the specific branch?