[INFO] fetching crate md_title 0.1.12...
[INFO] testing md_title-0.1.12 against 1.90.0 for beta-1.91-3
[INFO] extracting crate md_title 0.1.12 into /workspace/builds/worker-0-tc1/source
[INFO] started tweaking crates.io crate md_title 0.1.12
[INFO] removed 0 missing tests
[INFO] finished tweaking crates.io crate md_title 0.1.12
[INFO] tweaked toml for crates.io crate md_title 0.1.12 written to /workspace/builds/worker-0-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate md_title 0.1.12 on toolchain 1.90.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "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" "+1.90.0" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 101 packages to latest compatible versions
[INFO] [stderr]       Adding html2text v0.13.6 (available: v0.15.5)
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded xerr v0.1.16
[INFO] [stderr]   Downloaded loginit v0.1.18
[INFO] [stderr]   Downloaded match_token v0.1.0
[INFO] [stderr]   Downloaded string_cache_codegen v0.5.4
[INFO] [stderr]   Downloaded pastey v0.1.1
[INFO] [stderr]   Downloaded aok v0.1.17
[INFO] [stderr]   Downloaded markup5ever v0.14.1
[INFO] [stderr]   Downloaded html5ever v0.29.1
[INFO] [stderr]   Downloaded html2text v0.13.6
[INFO] [stderr]   Downloaded htmlize v1.0.6
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+1.90.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 3cbd6ba1eb392d88b3db2e5d9cb015741a33c95ef1da682653e0c60ed5bc2cbd
[INFO] running `Command { std: "docker" "start" "-a" "3cbd6ba1eb392d88b3db2e5d9cb015741a33c95ef1da682653e0c60ed5bc2cbd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "3cbd6ba1eb392d88b3db2e5d9cb015741a33c95ef1da682653e0c60ed5bc2cbd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "3cbd6ba1eb392d88b3db2e5d9cb015741a33c95ef1da682653e0c60ed5bc2cbd", kill_on_drop: false }`
[INFO] [stdout] 3cbd6ba1eb392d88b3db2e5d9cb015741a33c95ef1da682653e0c60ed5bc2cbd
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+1.90.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] ab4b83e113c2129edcbc530ce216d41b9e09ea280f4dff8be9a02c360bfd6367
[INFO] running `Command { std: "docker" "start" "-a" "ab4b83e113c2129edcbc530ce216d41b9e09ea280f4dff8be9a02c360bfd6367", kill_on_drop: false }`
[INFO] [stderr]    Compiling serde v1.0.228
[INFO] [stderr]    Compiling cfg-if v1.0.3
[INFO] [stderr]    Compiling mac v0.1.1
[INFO] [stderr]    Compiling precomputed-hash v0.1.1
[INFO] [stderr]    Compiling phf_shared v0.11.3
[INFO] [stderr]    Compiling lock_api v0.4.13
[INFO] [stderr]    Compiling htmlize v1.0.6
[INFO] [stderr]    Compiling unicode-width v0.2.1
[INFO] [stderr]    Compiling pastey v0.1.1
[INFO] [stderr]    Compiling nom v7.1.3
[INFO] [stderr]    Compiling match_token v0.1.0
[INFO] [stderr]    Compiling aok v0.1.17
[INFO] [stderr]    Compiling xerr v0.1.16
[INFO] [stderr]    Compiling futf v0.1.5
[INFO] [stderr]    Compiling parking_lot_core v0.9.11
[INFO] [stderr]    Compiling phf_generator v0.11.3
[INFO] [stderr]    Compiling phf v0.11.3
[INFO] [stderr]    Compiling tendril v0.4.3
[INFO] [stderr]    Compiling phf_codegen v0.11.3
[INFO] [stderr]    Compiling string_cache_codegen v0.5.4
[INFO] [stderr]    Compiling parking_lot v0.12.4
[INFO] [stderr]    Compiling markup5ever v0.14.1
[INFO] [stderr]    Compiling string_cache v0.8.9
[INFO] [stderr]    Compiling html5ever v0.29.1
[INFO] [stderr]    Compiling html2text v0.13.6
[INFO] [stderr]    Compiling md_title v0.1.12 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(const_trait_impl)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `md_title` (lib) due to 1 previous error
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] running `Command { std: "docker" "inspect" "ab4b83e113c2129edcbc530ce216d41b9e09ea280f4dff8be9a02c360bfd6367", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ab4b83e113c2129edcbc530ce216d41b9e09ea280f4dff8be9a02c360bfd6367", kill_on_drop: false }`
[INFO] [stdout] ab4b83e113c2129edcbc530ce216d41b9e09ea280f4dff8be9a02c360bfd6367