[INFO] cloning repository https://github.com/luciusmagn/permutation
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/luciusmagn/permutation" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fluciusmagn%2Fpermutation", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fluciusmagn%2Fpermutation'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] e6462bc72c1ba754a35c151ea5ad7f7665beb2cd
[INFO] checking luciusmagn/permutation against master#613bdd49978298648ed05ace086bd1ecad54b44a for pr-136458
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fluciusmagn%2Fpermutation" "/workspace/builds/worker-1-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc1/source'...
[INFO] [stderr] done.
[INFO] [stderr] fatal: update_ref failed for ref 'HEAD': cannot update ref 'refs/heads/master': couldn't write '/workspace/builds/worker-1-tc1/source/.git/refs/heads/master.lock'


failed to checkout https://github.com/luciusmagn/permutation

Caused by:
    command failed: exit status: 128