[INFO] cloning repository https://github.com/benreyn/rust-todo
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/benreyn/rust-todo" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbenreyn%2Frust-todo", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbenreyn%2Frust-todo'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 7711bfd99e449bbbcc73031966429444ea71b1a6
[INFO] testing benreyn/rust-todo against master#414482f6a0d4e7290f614300581a0b55442552a3 for pr-140985
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbenreyn%2Frust-todo" "/workspace/builds/worker-5-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-5-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-5-tc1/source/.git/refs/heads/master.lock'


failed to checkout https://github.com/benreyn/rust-todo

Caused by:
    command failed: exit status: 128