[INFO] cloning repository https://github.com/jrmoulton/rust_interview_questions
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/jrmoulton/rust_interview_questions" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fjrmoulton%2Frust_interview_questions", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fjrmoulton%2Frust_interview_questions'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] a30fa6e00534dfdd271dd29e8073fca04309a802
[INFO] testing jrmoulton/rust_interview_questions against 1.49.0 for beta-1.50-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fjrmoulton%2Frust_interview_questions" "/workspace/builds/worker-0/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-0/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/jrmoulton/rust_interview_questions on toolchain 1.49.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/jrmoulton/rust_interview_questions
[INFO] finished tweaking git repo https://github.com/jrmoulton/rust_interview_questions
[INFO] tweaked toml for git repo https://github.com/jrmoulton/rust_interview_questions written to /workspace/builds/worker-0/source/Cargo.toml
[INFO] crate git repo https://github.com/jrmoulton/rust_interview_questions already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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" "rustops/crates-build-env@sha256:c8ac004eab7d63a0ad09a2dde3d3353ba464f767bee4de425dc8f74c46a1905e" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 35892e89b5354255e4d207e8c210451661830b69f32c7c682aba040559f7089e
[INFO] running `Command { std: "docker" "start" "-a" "35892e89b5354255e4d207e8c210451661830b69f32c7c682aba040559f7089e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "35892e89b5354255e4d207e8c210451661830b69f32c7c682aba040559f7089e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "35892e89b5354255e4d207e8c210451661830b69f32c7c682aba040559f7089e", kill_on_drop: false }`
[INFO] [stdout] 35892e89b5354255e4d207e8c210451661830b69f32c7c682aba040559f7089e
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "rustops/crates-build-env@sha256:c8ac004eab7d63a0ad09a2dde3d3353ba464f767bee4de425dc8f74c46a1905e" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 0f4361d607b155498466e1a03018a7b96df9f4d24c6440f26a4ea0db408dc11d
[INFO] running `Command { std: "docker" "start" "-a" "0f4361d607b155498466e1a03018a7b96df9f4d24c6440f26a4ea0db408dc11d", kill_on_drop: false }`
[INFO] [stderr]    Compiling interview_questions v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/main.rs:3:1
[INFO] [stdout]   |
[INFO] [stdout] 3 | #![feature(non_ascii_idents)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `interview_questions`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "0f4361d607b155498466e1a03018a7b96df9f4d24c6440f26a4ea0db408dc11d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0f4361d607b155498466e1a03018a7b96df9f4d24c6440f26a4ea0db408dc11d", kill_on_drop: false }`
[INFO] [stdout] 0f4361d607b155498466e1a03018a7b96df9f4d24c6440f26a4ea0db408dc11d