[INFO] cloning repository https://github.com/zs856/rust-blockchain
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/zs856/rust-blockchain" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzs856%2Frust-blockchain", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzs856%2Frust-blockchain'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 370b3f9c5b0cca33d64f65f4484d6a62ceeb6501
[INFO] testing zs856/rust-blockchain against 1.76.0 for beta-1.77-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzs856%2Frust-blockchain" "/workspace/builds/worker-3-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/zs856/rust-blockchain on toolchain 1.76.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.76.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/zs856/rust-blockchain
[INFO] finished tweaking git repo https://github.com/zs856/rust-blockchain
[INFO] tweaked toml for git repo https://github.com/zs856/rust-blockchain written to /workspace/builds/worker-3-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/zs856/rust-blockchain already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.76.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+1.76.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 70c1c30e0b82287dc32b67e860829c3017416ebedc8d32fd5a43f756a3c944a1
[INFO] running `Command { std: "docker" "start" "-a" "70c1c30e0b82287dc32b67e860829c3017416ebedc8d32fd5a43f756a3c944a1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "70c1c30e0b82287dc32b67e860829c3017416ebedc8d32fd5a43f756a3c944a1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "70c1c30e0b82287dc32b67e860829c3017416ebedc8d32fd5a43f756a3c944a1", kill_on_drop: false }`
[INFO] [stdout] 70c1c30e0b82287dc32b67e860829c3017416ebedc8d32fd5a43f756a3c944a1
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "RUSTDOCFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+1.76.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] b9166eb583e332a9d68b7dc3634758a24535d5f98908ea14e9ef0ffb8e5e615d
[INFO] running `Command { std: "docker" "start" "-a" "b9166eb583e332a9d68b7dc3634758a24535d5f98908ea14e9ef0ffb8e5e615d", kill_on_drop: false }`
[INFO] [stderr] error: failed to create directory `/opt/rustwide/target/debug/.fingerprint/generic-array-528ce85e2989ef91`
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   No space left on device (os error 28)
[INFO] running `Command { std: "docker" "inspect" "b9166eb583e332a9d68b7dc3634758a24535d5f98908ea14e9ef0ffb8e5e615d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b9166eb583e332a9d68b7dc3634758a24535d5f98908ea14e9ef0ffb8e5e615d", kill_on_drop: false }`
[INFO] [stdout] b9166eb583e332a9d68b7dc3634758a24535d5f98908ea14e9ef0ffb8e5e615d
[INFO] testing zs856/rust-blockchain against beta-2024-02-10 for beta-1.77-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzs856%2Frust-blockchain" "/workspace/builds/worker-3-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/zs856/rust-blockchain on toolchain beta-2024-02-10
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2024-02-10" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/zs856/rust-blockchain
[INFO] finished tweaking git repo https://github.com/zs856/rust-blockchain
[INFO] tweaked toml for git repo https://github.com/zs856/rust-blockchain written to /workspace/builds/worker-3-tc2/source/Cargo.toml
[INFO] crate git repo https://github.com/zs856/rust-blockchain already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2024-02-10" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2024-02-10" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 860b33d8a520804369ec4fd3b8d1084874029b258838f3dcde196558f2b23c44
[INFO] running `Command { std: "docker" "start" "-a" "860b33d8a520804369ec4fd3b8d1084874029b258838f3dcde196558f2b23c44", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "860b33d8a520804369ec4fd3b8d1084874029b258838f3dcde196558f2b23c44", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "860b33d8a520804369ec4fd3b8d1084874029b258838f3dcde196558f2b23c44", kill_on_drop: false }`
[INFO] [stdout] 860b33d8a520804369ec4fd3b8d1084874029b258838f3dcde196558f2b23c44
[INFO] testing zs856/rust-blockchain against beta-2024-02-10 for beta-1.77-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzs856%2Frust-blockchain" "/workspace/builds/worker-3-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/zs856/rust-blockchain on toolchain beta-2024-02-10
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2024-02-10" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/zs856/rust-blockchain
[INFO] finished tweaking git repo https://github.com/zs856/rust-blockchain
[INFO] tweaked toml for git repo https://github.com/zs856/rust-blockchain written to /workspace/builds/worker-3-tc2/source/Cargo.toml
[INFO] crate git repo https://github.com/zs856/rust-blockchain already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2024-02-10" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2024-02-10" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 94dc12b3e45a22e745c296fa10bc268fcb68167f889b8fffd07f24c037e3b4c1
[INFO] running `Command { std: "docker" "start" "-a" "94dc12b3e45a22e745c296fa10bc268fcb68167f889b8fffd07f24c037e3b4c1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "94dc12b3e45a22e745c296fa10bc268fcb68167f889b8fffd07f24c037e3b4c1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "94dc12b3e45a22e745c296fa10bc268fcb68167f889b8fffd07f24c037e3b4c1", kill_on_drop: false }`
[INFO] [stdout] 94dc12b3e45a22e745c296fa10bc268fcb68167f889b8fffd07f24c037e3b4c1
[INFO] testing zs856/rust-blockchain against beta-2024-02-10 for beta-1.77-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzs856%2Frust-blockchain" "/workspace/builds/worker-3-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/zs856/rust-blockchain on toolchain beta-2024-02-10
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2024-02-10" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/zs856/rust-blockchain
[INFO] finished tweaking git repo https://github.com/zs856/rust-blockchain
[INFO] tweaked toml for git repo https://github.com/zs856/rust-blockchain written to /workspace/builds/worker-3-tc2/source/Cargo.toml
[INFO] crate git repo https://github.com/zs856/rust-blockchain already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2024-02-10" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2024-02-10" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] f00cc35ebd9b5f3ec3bd24855f3984789e10e7c5dc8226a24149d391c76702a1
[INFO] running `Command { std: "docker" "start" "-a" "f00cc35ebd9b5f3ec3bd24855f3984789e10e7c5dc8226a24149d391c76702a1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "f00cc35ebd9b5f3ec3bd24855f3984789e10e7c5dc8226a24149d391c76702a1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f00cc35ebd9b5f3ec3bd24855f3984789e10e7c5dc8226a24149d391c76702a1", kill_on_drop: false }`
[INFO] [stdout] f00cc35ebd9b5f3ec3bd24855f3984789e10e7c5dc8226a24149d391c76702a1
[INFO] testing zs856/rust-blockchain against beta-2024-02-10 for beta-1.77-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzs856%2Frust-blockchain" "/workspace/builds/worker-3-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/zs856/rust-blockchain on toolchain beta-2024-02-10
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2024-02-10" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/zs856/rust-blockchain
[INFO] finished tweaking git repo https://github.com/zs856/rust-blockchain
[INFO] tweaked toml for git repo https://github.com/zs856/rust-blockchain written to /workspace/builds/worker-3-tc2/source/Cargo.toml
[INFO] crate git repo https://github.com/zs856/rust-blockchain already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2024-02-10" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2024-02-10" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 5f216ebe51e6ad28f23ee7b113eeaa2aa76775dc27c553c976625c5541861c46
[INFO] running `Command { std: "docker" "start" "-a" "5f216ebe51e6ad28f23ee7b113eeaa2aa76775dc27c553c976625c5541861c46", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "5f216ebe51e6ad28f23ee7b113eeaa2aa76775dc27c553c976625c5541861c46", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5f216ebe51e6ad28f23ee7b113eeaa2aa76775dc27c553c976625c5541861c46", kill_on_drop: false }`
[INFO] [stdout] 5f216ebe51e6ad28f23ee7b113eeaa2aa76775dc27c553c976625c5541861c46
[INFO] testing zs856/rust-blockchain against beta-2024-02-10 for beta-1.77-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzs856%2Frust-blockchain" "/workspace/builds/worker-3-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/zs856/rust-blockchain on toolchain beta-2024-02-10
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2024-02-10" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/zs856/rust-blockchain
[INFO] finished tweaking git repo https://github.com/zs856/rust-blockchain
[INFO] tweaked toml for git repo https://github.com/zs856/rust-blockchain written to /workspace/builds/worker-3-tc2/source/Cargo.toml
[INFO] crate git repo https://github.com/zs856/rust-blockchain already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2024-02-10" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2024-02-10" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stderr] Error response from daemon: chown /var/lib/docker/overlay2/357872db4b72b46f40347ec9dc097c7d44c902cf5b35845df709e88b8e58f012/work/work: no such file or directory
[ERROR] this task or one of its parent failed!
[ERROR] command failed: exit status: 1
[ERROR] note: run with `RUST_BACKTRACE=1` to display a backtrace.
