[INFO] cloning repository https://github.com/gklijs/vados
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/gklijs/vados" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgklijs%2Fvados", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgklijs%2Fvados'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 85182a81f7675296c9dff4315d1831a7ada5699d
[INFO] checking gklijs/vados against master#0ef0dd24510b52da980889546fcd15254dc56a23 for pr-126452
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgklijs%2Fvados" "/workspace/builds/worker-6-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-6-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/gklijs/vados on toolchain 0ef0dd24510b52da980889546fcd15254dc56a23
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+0ef0dd24510b52da980889546fcd15254dc56a23" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/gklijs/vados
[INFO] finished tweaking git repo https://github.com/gklijs/vados
[INFO] tweaked toml for git repo https://github.com/gklijs/vados written to /workspace/builds/worker-6-tc1/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+0ef0dd24510b52da980889546fcd15254dc56a23" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 97 packages to latest compatible versions
[INFO] [stderr]       Adding askama v0.11.1 (latest: v0.12.1)
[INFO] [stderr]       Adding askama_derive v0.11.2 (latest: v0.12.5)
[INFO] [stderr]       Adding bitflags v1.3.2 (latest: v2.5.0)
[INFO] [stderr]       Adding fast_image_resize v0.7.0 (latest: v4.0.0)
[INFO] [stderr]       Adding humansize v1.1.1 (latest: v2.1.3)
[INFO] [stderr]       Adding image v0.24.9 (latest: v0.25.1)
[INFO] [stderr]       Adding minifier v0.0.42 (latest: v0.3.0)
[INFO] [stderr]       Adding pulldown-cmark v0.9.6 (latest: v0.11.0)
[INFO] [stderr]       Adding syn v1.0.109 (latest: v2.0.66)
[INFO] [stderr]       Adding toml v0.5.11 (latest: v0.8.14)
[INFO] [stderr]       Adding webp v0.2.6 (latest: v0.3.0)
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+0ef0dd24510b52da980889546fcd15254dc56a23" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded askama v0.11.1
[INFO] [stderr]   Downloaded askama_derive v0.11.2
[INFO] [stderr]   Downloaded askama_shared v0.12.2
[INFO] [stderr]   Downloaded fast_image_resize v0.7.0
[INFO] [stderr]   Downloaded minifier v0.0.42
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-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:dff56e7819e73ed36160586b3445e93eb0be776c16704aeeded9c3fb668b2384" "/opt/rustwide/cargo-home/bin/cargo" "+0ef0dd24510b52da980889546fcd15254dc56a23" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] ac11ccfd8c25d211499e4e20ac9aafd11ce455e1cbae8c23b16541969a68e8dd
[INFO] running `Command { std: "docker" "start" "-a" "ac11ccfd8c25d211499e4e20ac9aafd11ce455e1cbae8c23b16541969a68e8dd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "ac11ccfd8c25d211499e4e20ac9aafd11ce455e1cbae8c23b16541969a68e8dd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ac11ccfd8c25d211499e4e20ac9aafd11ce455e1cbae8c23b16541969a68e8dd", kill_on_drop: false }`
[INFO] [stdout] ac11ccfd8c25d211499e4e20ac9aafd11ce455e1cbae8c23b16541969a68e8dd
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-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=forbid" "-e" "RUSTDOCFLAGS=--cap-lints=forbid" "-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:dff56e7819e73ed36160586b3445e93eb0be776c16704aeeded9c3fb668b2384" "/opt/rustwide/cargo-home/bin/cargo" "+0ef0dd24510b52da980889546fcd15254dc56a23" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] ccbdfbce719f464b0d7498a83283894599ac42eac5fbe3ae3d0a16c288247dd7
[INFO] running `Command { std: "docker" "start" "-a" "ccbdfbce719f464b0d7498a83283894599ac42eac5fbe3ae3d0a16c288247dd7", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.85
[INFO] [stderr]    Compiling unicode-ident v1.0.12
[INFO] [stderr]    Compiling autocfg v1.3.0
[INFO] [stderr]    Compiling version_check v0.9.4
[INFO] [stderr]    Compiling libc v0.2.155
[INFO] [stderr]    Compiling crossbeam-utils v0.8.20
[INFO] [stderr]     Checking cfg-if v1.0.0
[INFO] [stderr]    Compiling serde v1.0.203
[INFO] [stderr]     Checking simd-adler32 v0.3.7
[INFO] [stderr]     Checking memchr v2.7.4
[INFO] [stderr]    Compiling rayon-core v1.12.1
[INFO] [stderr]     Checking adler v1.0.2
[INFO] [stderr]     Checking scopeguard v1.2.0
[INFO] [stderr]    Compiling syn v1.0.109
[INFO] [stderr]     Checking miniz_oxide v0.7.3
[INFO] [stderr]    Compiling unicase v2.7.0
[INFO] [stderr]    Compiling lock_api v0.4.12
[INFO] [stderr]    Compiling num-traits v0.2.19
[INFO] [stderr]     Checking crc32fast v1.4.2
[INFO] [stderr]     Checking crossbeam-epoch v0.9.18
[INFO] [stderr]    Compiling quote v1.0.36
[INFO] [stderr]    Compiling mime_guess v2.0.4
[INFO] [stderr]     Checking either v1.12.0
[INFO] [stderr]    Compiling once_cell v1.19.0
[INFO] [stderr]     Checking crossbeam-deque v0.8.5
[INFO] [stderr]    Compiling syn v2.0.66
[INFO] [stderr]     Checking smallvec v1.13.2
[INFO] [stderr]    Compiling jobserver v0.1.31
[INFO] [stderr]     Checking flate2 v1.0.30
[INFO] [stderr]     Checking spin v0.9.8
[INFO] [stderr]    Compiling cc v1.0.99
[INFO] [stderr]     Checking weezl v0.1.8
[INFO] [stderr]    Compiling minimal-lexical v0.2.1
[INFO] [stderr]     Checking rayon v1.10.0
[INFO] [stderr]    Compiling glob v0.3.1
[INFO] [stderr]    Compiling mime v0.3.17
[INFO] [stderr]     Checking flume v0.11.0
[INFO] [stderr]     Checking aho-corasick v1.1.3
[INFO] [stderr]     Checking zune-inflate v0.2.54
[INFO] [stderr]    Compiling nom v7.1.3
[INFO] [stderr]     Checking fdeflate v0.3.4
[INFO] [stderr]     Checking half v2.4.1
[INFO] [stderr]     Checking color_quant v1.1.0
[INFO] [stderr]    Compiling askama_escape v0.10.3
[INFO] [stderr]     Checking bitflags v1.3.2
[INFO] [stderr]     Checking regex-syntax v0.8.4
[INFO] [stderr]     Checking lebe v0.5.2
[INFO] [stderr]     Checking bytemuck v1.16.0
[INFO] [stderr]    Compiling thiserror v1.0.61
[INFO] [stderr]    Compiling libwebp-sys v0.9.5
[INFO] [stderr]    Compiling parking_lot_core v0.9.10
[INFO] [stderr]     Checking bit_field v0.10.2
[INFO] [stderr]     Checking exr v1.72.0
[INFO] [stderr]     Checking jpeg-decoder v0.3.1
[INFO] [stderr]     Checking qoi v0.4.1
[INFO] [stderr]    Compiling serde_derive v1.0.203
[INFO] [stderr]     Checking tiff v0.9.1
[INFO] [stderr]    Compiling thiserror-impl v1.0.61
[INFO] [stderr]     Checking png v0.17.13
[INFO] [stderr]     Checking regex-automata v0.4.7
[INFO] [stderr]     Checking gif v0.13.1
[INFO] [stderr]     Checking byteorder v1.5.0
[INFO] [stderr]     Checking humansize v1.1.1
[INFO] [stderr]    Compiling serde_json v1.0.117
[INFO] [stderr]    Compiling pulldown-cmark v0.9.6
[INFO] [stderr]     Checking percent-encoding v2.3.1
[INFO] [stderr]     Checking image v0.24.9
[INFO] [stderr]     Checking itoa v1.0.11
[INFO] [stderr]     Checking same-file v1.0.6
[INFO] [stderr]     Checking hashbrown v0.14.5
[INFO] [stderr]     Checking bitflags v2.5.0
[INFO] [stderr]     Checking macro-utils v0.1.3
[INFO] [stderr]     Checking ryu v1.0.18
[INFO] [stderr]     Checking walkdir v2.5.0
[INFO] [stderr]     Checking fast_image_resize v0.7.0
[INFO] [stderr]     Checking dashmap v5.5.3
[INFO] [stderr]     Checking regex v1.10.5
[INFO] [stderr]     Checking minifier v0.0.42
[INFO] [stderr]     Checking toml v0.5.11
[INFO] [stderr]     Checking askama_shared v0.12.2
[INFO] [stderr]     Checking webp v0.2.6
[INFO] [stderr]    Compiling askama_derive v0.11.2
[INFO] [stderr]     Checking askama v0.11.1
[INFO] [stderr]     Checking vados v0.0.3 (/opt/rustwide/workdir)
[INFO] [stdout] warning: field `title` is never read
[INFO] [stdout]    --> src/config_files.rs:128:16
[INFO] [stdout]     |
[INFO] [stdout] 127 | pub(crate) struct ImageList {
[INFO] [stdout]     |                   --------- field in this struct
[INFO] [stdout] 128 |     pub(crate) title: Option<String>,
[INFO] [stdout]     |                ^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `ImageList` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]     = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `title` is never read
[INFO] [stdout]    --> src/config_files.rs:128:16
[INFO] [stdout]     |
[INFO] [stdout] 127 | pub(crate) struct ImageList {
[INFO] [stdout]     |                   --------- field in this struct
[INFO] [stdout] 128 |     pub(crate) title: Option<String>,
[INFO] [stdout]     |                ^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `ImageList` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]     = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 10.84s
[INFO] running `Command { std: "docker" "inspect" "ccbdfbce719f464b0d7498a83283894599ac42eac5fbe3ae3d0a16c288247dd7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ccbdfbce719f464b0d7498a83283894599ac42eac5fbe3ae3d0a16c288247dd7", kill_on_drop: false }`
[INFO] [stdout] ccbdfbce719f464b0d7498a83283894599ac42eac5fbe3ae3d0a16c288247dd7
[INFO] checking gklijs/vados against try#d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9 for pr-126452
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgklijs%2Fvados" "/workspace/builds/worker-6-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-6-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/gklijs/vados on toolchain d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/gklijs/vados
[INFO] finished tweaking git repo https://github.com/gklijs/vados
[INFO] tweaked toml for git repo https://github.com/gklijs/vados written to /workspace/builds/worker-6-tc2/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[ERROR] error running command: no output for 300 seconds
[INFO] checking gklijs/vados against try#d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9 for pr-126452
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgklijs%2Fvados" "/workspace/builds/worker-6-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-6-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/gklijs/vados on toolchain d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/gklijs/vados
[INFO] finished tweaking git repo https://github.com/gklijs/vados
[INFO] tweaked toml for git repo https://github.com/gklijs/vados written to /workspace/builds/worker-6-tc2/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9" "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]     Blocking waiting for file lock on package cache
[ERROR] error running command: no output for 300 seconds
[INFO] checking gklijs/vados against try#d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9 for pr-126452
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgklijs%2Fvados" "/workspace/builds/worker-6-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-6-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/gklijs/vados on toolchain d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/gklijs/vados
[INFO] finished tweaking git repo https://github.com/gklijs/vados
[INFO] tweaked toml for git repo https://github.com/gklijs/vados written to /workspace/builds/worker-6-tc2/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9" "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]     Blocking waiting for file lock on package cache
[ERROR] error running command: no output for 300 seconds
[INFO] checking gklijs/vados against try#d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9 for pr-126452
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgklijs%2Fvados" "/workspace/builds/worker-6-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-6-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/gklijs/vados on toolchain d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/gklijs/vados
[INFO] finished tweaking git repo https://github.com/gklijs/vados
[INFO] tweaked toml for git repo https://github.com/gklijs/vados written to /workspace/builds/worker-6-tc2/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9" "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]     Blocking waiting for file lock on package cache
[ERROR] error running command: no output for 300 seconds
[INFO] checking gklijs/vados against try#d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9 for pr-126452
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgklijs%2Fvados" "/workspace/builds/worker-6-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-6-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/gklijs/vados on toolchain d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/gklijs/vados
[INFO] finished tweaking git repo https://github.com/gklijs/vados
[INFO] tweaked toml for git repo https://github.com/gklijs/vados written to /workspace/builds/worker-6-tc2/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+d9cbfeb054d7bd02cf942e6d32c1c0a91f042ce9" "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]     Blocking waiting for file lock on package cache
[ERROR] error running command: no output for 300 seconds
[ERROR] this task or one of its parent failed!
[ERROR] no output for 300 seconds
[ERROR] note: run with `RUST_BACKTRACE=1` to display a backtrace.