[INFO] cloning repository https://github.com/rascal-gitchan/prototype_block
[INFO] running `"git" "-c" "credential.helper=" "-c" "credential.helper=/mnt/big/crater/work/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/rascal-gitchan/prototype_block" "work/cache/git-repos/https%3A%2F%2Fgithub.com%2Frascal-gitchan%2Fprototype_block"`
[INFO] [stderr] Cloning into bare repository 'work/cache/git-repos/https%3A%2F%2Fgithub.com%2Frascal-gitchan%2Fprototype_block'...
[INFO] [stderr] fatal: credential helper '/mnt/big/crater/work/cargo-home/bin/git-credential-null' told us to quit
[ERROR] this task or one of its parent failed!
[ERROR] can't fetch private git repositories