[INFO] cloning repository https://github.com/erebe/memcached_proxy
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/erebe/memcached_proxy" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ferebe%2Fmemcached_proxy", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ferebe%2Fmemcached_proxy'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 3bbfe52bf123262f7d680b22d839b1f034f957a4
[INFO] checking erebe/memcached_proxy against master#5337252b9952fdd9482ed6a4add17254e5bd2c40 for pr-138785
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ferebe%2Fmemcached_proxy" "/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/erebe/memcached_proxy

Caused by:
    command failed: exit status: 128