[INFO] cloning repository https://github.com/magodo/grop
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/magodo/grop" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmagodo%2Fgrop", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmagodo%2Fgrop'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 8c4513020ba075c2b9b05befad50f1675cc9b844
[INFO] checking magodo/grop against master#8a65ee08296b36342bf7c3cdc15312ccbc357227 for pr-142704
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmagodo%2Fgrop" "/workspace/builds/worker-6-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-6-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-6-tc1/source/.git/refs/heads/master.lock'


failed to checkout https://github.com/magodo/grop

Caused by:
    command failed: exit status: 128