[INFO] fetching crate mamba 0.3.0...
[INFO] documenting mamba-0.3.0 against 1.46.0 for beta-1.47-rustdoc-1
[INFO] extracting crate mamba 0.3.0 into /workspace/builds/worker-6/source
[INFO] validating manifest of crates.io crate mamba 0.3.0 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 mamba 0.3.0
[INFO] finished tweaking crates.io crate mamba 0.3.0
[INFO] tweaked toml for crates.io crate mamba 0.3.0 written to /workspace/builds/worker-6/source/Cargo.toml
[INFO] crate crates.io crate mamba 0.3.0 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-6/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/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] 183a0c523f29044a33abe9429502627d7e3d673ea5c62652c14b9d8fa9fcae6a
[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" "183a0c523f29044a33abe9429502627d7e3d673ea5c62652c14b9d8fa9fcae6a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "183a0c523f29044a33abe9429502627d7e3d673ea5c62652c14b9d8fa9fcae6a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "183a0c523f29044a33abe9429502627d7e3d673ea5c62652c14b9d8fa9fcae6a", kill_on_drop: false }`
[INFO] [stdout] 183a0c523f29044a33abe9429502627d7e3d673ea5c62652c14b9d8fa9fcae6a
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/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] [stdout] f7ec06540c9ec993a98b60557ae07625709b0f76ae39df4d1b94841322998be6
[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" "f7ec06540c9ec993a98b60557ae07625709b0f76ae39df4d1b94841322998be6", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling syn v1.0.13
[INFO] [stderr]     Checking predicates-core v1.0.0
[INFO] [stderr]    Compiling escargot v0.3.1
[INFO] [stderr]     Checking treeline v0.1.0
[INFO] [stderr]     Checking bytecount v0.3.2
[INFO] [stderr]     Checking unicode_names2 v0.2.2
[INFO] [stderr]     Checking wtf8 v0.0.3
[INFO] [stderr]     Checking pathdiff v0.1.0
[INFO] [stderr]    Compiling num-traits v0.2.10
[INFO] [stderr]    Compiling num-integer v0.1.41
[INFO] [stderr]    Compiling num-bigint v0.2.4
[INFO] [stderr]     Checking nom v4.2.3
[INFO] [stderr]     Checking clap v2.33.0
[INFO] [stderr]     Checking loggerv v0.7.2
[INFO] [stderr]     Checking tempfile v3.1.0
[INFO] [stderr]     Checking predicates-tree v1.0.0
[INFO] [stderr]     Checking predicates v1.0.2
[INFO] [stderr]     Checking nom_locate v0.3.1
[INFO] [stderr]     Checking python-parser v0.1.0
[INFO] [stderr]    Compiling serde_derive v1.0.104
[INFO] [stderr]     Checking serde v1.0.104
[INFO] [stderr]     Checking serde_json v1.0.44
[INFO] [stderr]     Checking assert_cmd v0.10.2
[INFO] [stderr]  Documenting mamba v0.3.0 (/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(drain_filter)]
[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 `mamba`.
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type lib --crate-name mamba 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 ansi_term=/opt/rustwide/target/debug/deps/libansi_term-a4535ac1495c8e48.rmeta --extern assert_cmd=/opt/rustwide/target/debug/deps/libassert_cmd-e1b850bee5058b4a.rmeta --extern clap=/opt/rustwide/target/debug/deps/libclap-c0527544faeda36f.rmeta --extern glob=/opt/rustwide/target/debug/deps/libglob-91c2b32d0ceb9511.rmeta --extern itertools=/opt/rustwide/target/debug/deps/libitertools-5ad68357c26dda65.rmeta --extern log=/opt/rustwide/target/debug/deps/liblog-f96ba0118540bef9.rmeta --extern loggerv=/opt/rustwide/target/debug/deps/libloggerv-0cb4432394a40e92.rmeta --extern pathdiff=/opt/rustwide/target/debug/deps/libpathdiff-afc3c1be3de7f110.rmeta --extern python_parser=/opt/rustwide/target/debug/deps/libpython_parser-8d721a992033f9bd.rmeta --extern tempfile=/opt/rustwide/target/debug/deps/libtempfile-db39c44737c982b0.rmeta --cap-lints=warn` (exit code: 1)
[INFO] running `Command { std: "docker" "inspect" "f7ec06540c9ec993a98b60557ae07625709b0f76ae39df4d1b94841322998be6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f7ec06540c9ec993a98b60557ae07625709b0f76ae39df4d1b94841322998be6", kill_on_drop: false }`
[INFO] [stdout] f7ec06540c9ec993a98b60557ae07625709b0f76ae39df4d1b94841322998be6