Orbot website points to wrong svn location
https://guardianproject.info/apps/orbot/ is sending people to https://svn.torproject.org/cgi-bin/viewvc.cgi/projects/android/trunk/Orbot/ which isn't going to work. You can't svn co from a cgi script.
The correct url is https://svn.torproject.org/svn/projects/android/trunk/Orbot/