[INFO] cloning repository https://github.com/mdabir1203/GPT2Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/mdabir1203/GPT2Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmdabir1203%2FGPT2Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmdabir1203%2FGPT2Rust'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] de650b66f4bff5fd3ed235b570b2194efb1de2a5
[INFO] checking mdabir1203/GPT2Rust against master#1fe72d35998dea48aeecaf7fc07783b0b553f24f for pr-154992-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmdabir1203%2FGPT2Rust" "/workspace/builds/worker-4-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4-tc1/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/mdabir1203/GPT2Rust
[INFO] finished tweaking git repo https://github.com/mdabir1203/GPT2Rust
[INFO] tweaked toml for git repo https://github.com/mdabir1203/GPT2Rust written to /workspace/builds/worker-4-tc1/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/mdabir1203/GPT2Rust on toolchain 1fe72d35998dea48aeecaf7fc07783b0b553f24f
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1fe72d35998dea48aeecaf7fc07783b0b553f24f" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1fe72d35998dea48aeecaf7fc07783b0b553f24f" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr] error: failed to select a version for `nix`.
[INFO] [stderr]     ... required by package `mini-docker v0.1.0 (/workspace/builds/worker-4-tc1/source)`
[INFO] [stderr] versions that meet the requirements `^0.27` are: 0.27.1, 0.27.0
[INFO] [stderr] 
[INFO] [stderr] package `mini-docker` depends on `nix` with feature `unistd` but `nix` does not have that feature.
[INFO] [stderr] help: available features: acct, aio, default, dir, env, event, feature, fs, hostname, inotify, ioctl, kmod, memoffset, mman, mount, mqueue, net, personality, pin-utils, poll, process, pthread, ptrace, quota, reboot, resource, sched, signal, socket, term, time, ucontext, uio, user, zerocopy
[INFO] [stderr] 
[INFO] [stderr] 
[INFO] [stderr] failed to select a version for `nix` which could resolve this conflict


overridden task result to prepare-fail:unknown

Caused by:
    0: uncategorized prepare error
    1: command failed: exit status: 101
       
           Blocking waiting for file lock on package cache
           Updating crates.io index
       error: failed to select a version for `nix`.
           ... required by package `mini-docker v0.1.0 (/workspace/builds/worker-4-tc1/source)`
       versions that meet the requirements `^0.27` are: 0.27.1, 0.27.0
       
       package `mini-docker` depends on `nix` with feature `unistd` but `nix` does not have that feature.
       help: available features: acct, aio, default, dir, env, event, feature, fs, hostname, inotify, ioctl, kmod, memoffset, mman, mount, mqueue, net, personality, pin-utils, poll, process, pthread, ptrace, quota, reboot, resource, sched, signal, socket, term, time, ucontext, uio, user, zerocopy
       
       
       failed to select a version for `nix` which could resolve this conflict