[INFO] cloning repository https://github.com/geoffjay/git-utils [INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/geoffjay/git-utils" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgeoffjay%2Fgit-utils", kill_on_drop: false }` [INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgeoffjay%2Fgit-utils'... [INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }` [INFO] [stdout] f77d39990a3e6c7b3642c74999e6fb63b6e89983 [INFO] checking geoffjay/git-utils against master#05eac57ef6668c9d181b65aceb96b1e7881f60be for pr-127656 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgeoffjay%2Fgit-utils" "/workspace/builds/worker-1-tc1/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc1/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/geoffjay/git-utils on toolchain 05eac57ef6668c9d181b65aceb96b1e7881f60be [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+05eac57ef6668c9d181b65aceb96b1e7881f60be" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/geoffjay/git-utils [INFO] finished tweaking git repo https://github.com/geoffjay/git-utils [INFO] tweaked toml for git repo https://github.com/geoffjay/git-utils written to /workspace/builds/worker-1-tc1/source/Cargo.toml [INFO] crate git repo https://github.com/geoffjay/git-utils 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" "+05eac57ef6668c9d181b65aceb96b1e7881f60be" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] [stderr] Downloading crates ... [INFO] [stderr] Downloaded git2 v0.18.0 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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" "+05eac57ef6668c9d181b65aceb96b1e7881f60be" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] 250bb708a9c56d522d5b9c931c4f9c34c01032ff37136b1b0f6a026454f1b0c8 [INFO] running `Command { std: "docker" "start" "-a" "250bb708a9c56d522d5b9c931c4f9c34c01032ff37136b1b0f6a026454f1b0c8", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "250bb708a9c56d522d5b9c931c4f9c34c01032ff37136b1b0f6a026454f1b0c8", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "250bb708a9c56d522d5b9c931c4f9c34c01032ff37136b1b0f6a026454f1b0c8", kill_on_drop: false }` [INFO] [stdout] 250bb708a9c56d522d5b9c931c4f9c34c01032ff37136b1b0f6a026454f1b0c8 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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" "+05eac57ef6668c9d181b65aceb96b1e7881f60be" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] bb1295300548465e056dd1850ddbf45daa2c37b314a46014206115634030c9fa [INFO] running `Command { std: "docker" "start" "-a" "bb1295300548465e056dd1850ddbf45daa2c37b314a46014206115634030c9fa", kill_on_drop: false }` [INFO] [stderr] error: failed to create directory `/opt/rustwide/target/debug/.fingerprint/jobserver-15a619028cddc0f0` [INFO] [stderr] [INFO] [stderr] Caused by: [INFO] [stderr] No space left on device (os error 28) [INFO] running `Command { std: "docker" "inspect" "bb1295300548465e056dd1850ddbf45daa2c37b314a46014206115634030c9fa", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "bb1295300548465e056dd1850ddbf45daa2c37b314a46014206115634030c9fa", kill_on_drop: false }` [INFO] [stdout] bb1295300548465e056dd1850ddbf45daa2c37b314a46014206115634030c9fa [INFO] checking geoffjay/git-utils against try#0c9c19b42881b7ee3d3f268d2369726c7f8dddfd for pr-127656 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgeoffjay%2Fgit-utils" "/workspace/builds/worker-1-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/geoffjay/git-utils on toolchain 0c9c19b42881b7ee3d3f268d2369726c7f8dddfd [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/geoffjay/git-utils [INFO] finished tweaking git repo https://github.com/geoffjay/git-utils [INFO] tweaked toml for git repo https://github.com/geoffjay/git-utils written to /workspace/builds/worker-1-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/geoffjay/git-utils 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" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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:dff56e7819e73ed36160586b3445e93eb0be776c16704aeeded9c3fb668b2384" "/opt/rustwide/cargo-home/bin/cargo" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] e6215d853456bd51961f537de95c3e4dd889445c82a405a4e4b9679f12b3f014 [INFO] running `Command { std: "docker" "start" "-a" "e6215d853456bd51961f537de95c3e4dd889445c82a405a4e4b9679f12b3f014", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "e6215d853456bd51961f537de95c3e4dd889445c82a405a4e4b9679f12b3f014", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "e6215d853456bd51961f537de95c3e4dd889445c82a405a4e4b9679f12b3f014", kill_on_drop: false }` [INFO] [stdout] e6215d853456bd51961f537de95c3e4dd889445c82a405a4e4b9679f12b3f014 [INFO] checking geoffjay/git-utils against try#0c9c19b42881b7ee3d3f268d2369726c7f8dddfd for pr-127656 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgeoffjay%2Fgit-utils" "/workspace/builds/worker-1-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/geoffjay/git-utils on toolchain 0c9c19b42881b7ee3d3f268d2369726c7f8dddfd [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/geoffjay/git-utils [INFO] finished tweaking git repo https://github.com/geoffjay/git-utils [INFO] tweaked toml for git repo https://github.com/geoffjay/git-utils written to /workspace/builds/worker-1-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/geoffjay/git-utils 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" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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:dff56e7819e73ed36160586b3445e93eb0be776c16704aeeded9c3fb668b2384" "/opt/rustwide/cargo-home/bin/cargo" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] 8d37bf155a7a40252ebdfa482901e844830ac9977f9dc3440e80c7a9a2d1e5e7 [INFO] running `Command { std: "docker" "start" "-a" "8d37bf155a7a40252ebdfa482901e844830ac9977f9dc3440e80c7a9a2d1e5e7", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "8d37bf155a7a40252ebdfa482901e844830ac9977f9dc3440e80c7a9a2d1e5e7", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "8d37bf155a7a40252ebdfa482901e844830ac9977f9dc3440e80c7a9a2d1e5e7", kill_on_drop: false }` [INFO] [stdout] 8d37bf155a7a40252ebdfa482901e844830ac9977f9dc3440e80c7a9a2d1e5e7 [INFO] checking geoffjay/git-utils against try#0c9c19b42881b7ee3d3f268d2369726c7f8dddfd for pr-127656 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgeoffjay%2Fgit-utils" "/workspace/builds/worker-1-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/geoffjay/git-utils on toolchain 0c9c19b42881b7ee3d3f268d2369726c7f8dddfd [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/geoffjay/git-utils [INFO] finished tweaking git repo https://github.com/geoffjay/git-utils [INFO] tweaked toml for git repo https://github.com/geoffjay/git-utils written to /workspace/builds/worker-1-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/geoffjay/git-utils 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" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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:dff56e7819e73ed36160586b3445e93eb0be776c16704aeeded9c3fb668b2384" "/opt/rustwide/cargo-home/bin/cargo" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stderr] Error response from daemon: mkdir /var/lib/docker/overlay2/6565c7254e0b42d448034f754b06150d7d558e02461587c5f6ca7db20a0ad452/merged/opt/rustwide: no space left on device [INFO] checking geoffjay/git-utils against try#0c9c19b42881b7ee3d3f268d2369726c7f8dddfd for pr-127656 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgeoffjay%2Fgit-utils" "/workspace/builds/worker-1-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/geoffjay/git-utils on toolchain 0c9c19b42881b7ee3d3f268d2369726c7f8dddfd [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/geoffjay/git-utils [INFO] finished tweaking git repo https://github.com/geoffjay/git-utils [INFO] tweaked toml for git repo https://github.com/geoffjay/git-utils written to /workspace/builds/worker-1-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/geoffjay/git-utils 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" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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:dff56e7819e73ed36160586b3445e93eb0be776c16704aeeded9c3fb668b2384" "/opt/rustwide/cargo-home/bin/cargo" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stderr] Error response from daemon: chown /var/lib/docker/overlay2/adf5520e1feea0d9b1dd6328d5ecc8f88308d464f764a6fe97230f8333a6c2f6/work/work: no such file or directory [INFO] checking geoffjay/git-utils against try#0c9c19b42881b7ee3d3f268d2369726c7f8dddfd for pr-127656 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fgeoffjay%2Fgit-utils" "/workspace/builds/worker-1-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/geoffjay/git-utils on toolchain 0c9c19b42881b7ee3d3f268d2369726c7f8dddfd [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/geoffjay/git-utils [INFO] finished tweaking git repo https://github.com/geoffjay/git-utils [INFO] tweaked toml for git repo https://github.com/geoffjay/git-utils written to /workspace/builds/worker-1-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/geoffjay/git-utils 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" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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:dff56e7819e73ed36160586b3445e93eb0be776c16704aeeded9c3fb668b2384" "/opt/rustwide/cargo-home/bin/cargo" "+0c9c19b42881b7ee3d3f268d2369726c7f8dddfd" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stderr] Error response from daemon: mkdir /var/lib/docker/overlay2/1bdf7c9dcd83e816e5475452892f7bbf9dfcecb1e8c25224b76bd0bbb9072b2e/merged: no space left on device [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.