[INFO] cloning repository https://github.com/epsxy/rust-learn
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/epsxy/rust-learn" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fepsxy%2Frust-learn", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fepsxy%2Frust-learn'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] b68e410df2d207c0d6c3013c75bc4479b4e0597e
[INFO] checking epsxy/rust-learn against master#068609ce766e55d2e7371cd2a86143a6d7e8e2e4 for pr-138952
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fepsxy%2Frust-learn" "/workspace/builds/worker-7-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-7-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-7-tc1/source/.git/refs/heads/master.lock'


failed to checkout https://github.com/epsxy/rust-learn

Caused by:
    command failed: exit status: 128