About 1 min 45 seconds into building R on windows, it fails. I've restarted the build another two times. Same result. If I restart a build that has succeeded in the past (14 hrs ago), it fails to install R on windows.
Unfortunately the log does not provide useful output for this case, so it is hard to tell what is going wrong. However we are getting the same build failure on the setup-r checks, I will look into it and see if I can diagnose what is going wrong.