[INFO] fetching crate mech-server 0.0.4...
[INFO] checking mech-server-0.0.4 against beta for pr-78714
[INFO] extracting crate mech-server 0.0.4 into /workspace/builds/worker-2/source
[INFO] validating manifest of crates.io crate mech-server 0.0.4 on toolchain beta
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate mech-server 0.0.4
[INFO] finished tweaking crates.io crate mech-server 0.0.4
[INFO] tweaked toml for crates.io crate mech-server 0.0.4 written to /workspace/builds/worker-2/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta" "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" "+beta" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 28ca2ed904b13c0998b73c8b5824c2801d86660c0fa1bfd9f41cc7b2e4871035
[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" "28ca2ed904b13c0998b73c8b5824c2801d86660c0fa1bfd9f41cc7b2e4871035", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "28ca2ed904b13c0998b73c8b5824c2801d86660c0fa1bfd9f41cc7b2e4871035", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "28ca2ed904b13c0998b73c8b5824c2801d86660c0fa1bfd9f41cc7b2e4871035", kill_on_drop: false }`
[INFO] [stdout] 28ca2ed904b13c0998b73c8b5824c2801d86660c0fa1bfd9f41cc7b2e4871035
[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" "RUSTFLAGS=--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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+beta" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 1427420b7067da0a491e24b46ae1cc5ecf1f86db18883929e1248f9eb810c372
[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" "1427420b7067da0a491e24b46ae1cc5ecf1f86db18883929e1248f9eb810c372", kill_on_drop: false }`
[INFO] [stderr]    Compiling serde v1.0.117
[INFO] [stderr]     Checking regex-syntax v0.6.21
[INFO] [stderr]    Compiling memchr v2.3.4
[INFO] [stderr]     Checking ahash v0.3.8
[INFO] [stderr]     Checking arrayvec v0.5.2
[INFO] [stderr]     Checking sequence_trie v0.3.6
[INFO] [stderr]     Checking term v0.4.6
[INFO] [stderr]     Checking same-file v0.1.3
[INFO] [stderr]    Compiling hashbrown v0.7.2
[INFO] [stderr]     Checking try_from v0.3.2
[INFO] [stderr]    Compiling libloading v0.5.2
[INFO] [stderr]     Checking textwrap v0.11.0
[INFO] [stderr]     Checking getrandom v0.1.15
[INFO] [stderr]     Checking atty v0.2.14
[INFO] [stderr]    Compiling rand_os v0.1.3
[INFO] [stderr]     Checking walkdir v1.0.7
[INFO] [stderr]     Checking flate2 v1.0.19
[INFO] [stderr]     Checking num-traits v0.1.43
[INFO] [stderr]     Checking block-buffer v0.7.3
[INFO] [stderr]     Checking openssl v0.10.30
[INFO] [stderr]     Checking mio-extras v2.0.6
[INFO] [stderr]     Checking uuid v0.7.4
[INFO] [stderr]     Checking clap v2.33.3
[INFO] [stderr]     Checking cookie v0.12.0
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]    Compiling rand v0.6.5
[INFO] [stderr]     Checking sha-1 v0.8.2
[INFO] [stderr]     Checking term-painter v0.2.4
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]   --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/hashbrown-0.7.2/src/lib.rs:15:5
[INFO] [stdout]    |
[INFO] [stdout] 15 | /     feature(
[INFO] [stdout] 16 | |         alloc_layout_extra,
[INFO] [stdout] 17 | |         allocator_api,
[INFO] [stdout] 18 | |         ptr_offset_from,
[INFO] [stdout] ...  |
[INFO] [stdout] 22 | |         specialization,
[INFO] [stdout] 23 | |     )
[INFO] [stdout]    | |_____^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Checking tokio v0.1.22
[INFO] [stderr]     Checking rand_chacha v0.2.2
[INFO] [stderr]     Checking lexical-core v0.7.4
[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 `hashbrown`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "1427420b7067da0a491e24b46ae1cc5ecf1f86db18883929e1248f9eb810c372", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1427420b7067da0a491e24b46ae1cc5ecf1f86db18883929e1248f9eb810c372", kill_on_drop: false }`
[INFO] [stdout] 1427420b7067da0a491e24b46ae1cc5ecf1f86db18883929e1248f9eb810c372