[INFO] fetching crate zub 0.3.14...
[INFO] documenting zub-0.3.14 against 1.46.0 for beta-1.47-rustdoc-1
[INFO] extracting crate zub 0.3.14 into /workspace/builds/worker-2/source
[INFO] validating manifest of crates.io crate zub 0.3.14 on toolchain 1.46.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.46.0" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate zub 0.3.14
[INFO] finished tweaking crates.io crate zub 0.3.14
[INFO] tweaked toml for crates.io crate zub 0.3.14 written to /workspace/builds/worker-2/source/Cargo.toml
[INFO] crate crates.io crate zub 0.3.14 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.46.0" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/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:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+1.46.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] e4cb5644abc830dc6f12b1674caf2a3c95965fc0ea0e1067f52847f0155fe2ac
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "e4cb5644abc830dc6f12b1674caf2a3c95965fc0ea0e1067f52847f0155fe2ac", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "e4cb5644abc830dc6f12b1674caf2a3c95965fc0ea0e1067f52847f0155fe2ac", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e4cb5644abc830dc6f12b1674caf2a3c95965fc0ea0e1067f52847f0155fe2ac", kill_on_drop: false }`
[INFO] [stdout] e4cb5644abc830dc6f12b1674caf2a3c95965fc0ea0e1067f52847f0155fe2ac
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/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" "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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+1.46.0" "doc" "--frozen" "--no-deps" "--document-private-items" "--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] 4084f9732a28be2fc6a54102c9c91a58428d19c361f2c1d6656d1939176fff12
[INFO] running `Command { std: "docker" "start" "-a" "4084f9732a28be2fc6a54102c9c91a58428d19c361f2c1d6656d1939176fff12", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.69
[INFO] [stderr]    Compiling ryu v1.0.4
[INFO] [stderr]    Compiling proc-macro2 v1.0.12
[INFO] [stderr]    Compiling serde v1.0.106
[INFO] [stderr]    Compiling syn v1.0.18
[INFO] [stderr]    Compiling proc-macro2 v0.4.30
[INFO] [stderr]    Compiling typenum v1.12.0
[INFO] [stderr]    Compiling itoa v0.4.5
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling version_check v0.9.1
[INFO] [stderr]    Compiling autocfg v1.0.0
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]     Checking ahash v0.3.3
[INFO] [stderr]     Checking rand_xoshiro v0.4.0
[INFO] [stderr]    Compiling im-rc v14.3.0
[INFO] [stderr]    Compiling hashbrown v0.7.2
[INFO] [stderr]    Compiling quote v1.0.4
[INFO] [stderr]    Compiling quote v0.6.13
[INFO] [stderr]     Checking atty v0.2.14
[INFO] [stderr]     Checking thread-id v3.3.0
[INFO] [stderr]     Checking colored v1.9.3
[INFO] [stderr]     Checking bitmaps v2.1.0
[INFO] [stderr]     Checking sized-chunks v0.5.3
[INFO] [stderr]     Checking serde_json v1.0.52
[INFO] [stderr]    Compiling serde_derive v1.0.106
[INFO] [stderr]    Compiling flame v0.2.2
[INFO] [stderr]    Compiling flamer v0.3.0
[INFO] [stderr]  Documenting zub v0.3.14 (/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(vec_drain_as_slice)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: Compilation failed, aborting rustdoc
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 2 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: Could not document `zub`.
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type lib --crate-name zub src/lib.rs -o /opt/rustwide/target/doc --error-format=json --json=diagnostic-rendered-ansi --document-private-items -L dependency=/opt/rustwide/target/debug/deps --extern colored=/opt/rustwide/target/debug/deps/libcolored-f1d34c1bbe59d099.rmeta --extern flame=/opt/rustwide/target/debug/deps/libflame-28ae867f44f3974c.rmeta --extern flamer=/opt/rustwide/target/debug/deps/libflamer-f215ce7def3fcaa4.so --extern fnv=/opt/rustwide/target/debug/deps/libfnv-7722d5952f112cf5.rmeta --extern hashbrown=/opt/rustwide/target/debug/deps/libhashbrown-b90ca0b9365ad6ea.rmeta --extern im_rc=/opt/rustwide/target/debug/deps/libim_rc-ec7c332613c84416.rmeta --cap-lints=warn` (exit code: 1)
[INFO] running `Command { std: "docker" "inspect" "4084f9732a28be2fc6a54102c9c91a58428d19c361f2c1d6656d1939176fff12", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "4084f9732a28be2fc6a54102c9c91a58428d19c361f2c1d6656d1939176fff12", kill_on_drop: false }`
[INFO] [stdout] 4084f9732a28be2fc6a54102c9c91a58428d19c361f2c1d6656d1939176fff12