Empty download_url key
Over the past few days, I have noticed a few individual builds have no download_url key in builds.json, which means we cannot download any files for that build for testing.
https://github.com/ClangBuiltLinux/continuous-integration2/runs/6483098845?check_suite_focus=true#step:5:155 https://github.com/ClangBuiltLinux/continuous-integration2/runs/6483099166?check_suite_focus=true#step:5:155 https://github.com/ClangBuiltLinux/continuous-integration2/runs/6483108720?check_suite_focus=true#step:5:155 https://github.com/ClangBuiltLinux/continuous-integration2/runs/6483036715?check_suite_focus=true#step:5:155 https://github.com/ClangBuiltLinux/continuous-integration2/runs/6491950499?check_suite_focus=true#step:5:154 https://github.com/ClangBuiltLinux/continuous-integration2/runs/6493108648?check_suite_focus=true#step:5:151 https://github.com/ClangBuiltLinux/continuous-integration2/runs/6493370078?check_suite_focus=true#step:5:155 https://github.com/ClangBuiltLinux/continuous-integration2/runs/6493370592?check_suite_focus=true#step:5:155 https://github.com/ClangBuiltLinux/continuous-integration2/runs/6493370812?check_suite_focus=true#step:5:158