[INFO] cloning repository https://github.com/zackartz/pg-bot
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/zackartz/pg-bot" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzackartz%2Fpg-bot", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzackartz%2Fpg-bot'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] e967049ad3570cd7c00860c4c626f0fb237cf42c
[INFO] testing zackartz/pg-bot against master#552a959051cebf8f88a8f558399baf733bec9ce0 for pr-136932
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzackartz%2Fpg-bot" "/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/zackartz/pg-bot

Caused by:
    command failed: exit status: 128