[INFO] fetching crate boomerang 0.1.0...
[INFO] testing boomerang-0.1.0 against 1.55.0 for beta-1.56-1
[INFO] extracting crate boomerang 0.1.0 into /workspace/builds/worker-20/source
[INFO] validating manifest of crates.io crate boomerang 0.1.0 on toolchain 1.55.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate boomerang 0.1.0
[INFO] finished tweaking crates.io crate boomerang 0.1.0
[INFO] tweaked toml for crates.io crate boomerang 0.1.0 written to /workspace/builds/worker-20/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-20/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-20/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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 30596efc3721fbabd9282374e053d588b852e14b4ac379f38ce006cc34d064b0
[INFO] running `Command { std: "docker" "start" "-a" "30596efc3721fbabd9282374e053d588b852e14b4ac379f38ce006cc34d064b0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "30596efc3721fbabd9282374e053d588b852e14b4ac379f38ce006cc34d064b0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "30596efc3721fbabd9282374e053d588b852e14b4ac379f38ce006cc34d064b0", kill_on_drop: false }`
[INFO] [stdout] 30596efc3721fbabd9282374e053d588b852e14b4ac379f38ce006cc34d064b0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-20/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-20/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 4d3b092134f2553ea6c460109a4450c834b6dc5f0e01fc965bb42fe4e0d177b3
[INFO] running `Command { std: "docker" "start" "-a" "4d3b092134f2553ea6c460109a4450c834b6dc5f0e01fc965bb42fe4e0d177b3", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling proc-macro2 v1.0.29
[INFO] [stderr]    Compiling unicode-xid v0.2.2
[INFO] [stderr]    Compiling syn v1.0.76
[INFO] [stderr]    Compiling memchr v2.4.1
[INFO] [stderr]    Compiling fnv v1.0.7
[INFO] [stderr]    Compiling ident_case v1.0.1
[INFO] [stderr]    Compiling strsim v0.9.3
[INFO] [stderr]    Compiling regex-syntax v0.6.25
[INFO] [stderr]    Compiling hashbrown v0.11.2
[INFO] [stderr]    Compiling fixedbitset v0.2.0
[INFO] [stderr]    Compiling convert_case v0.4.0
[INFO] [stderr]    Compiling num-traits v0.2.14
[INFO] [stderr]    Compiling num-integer v0.1.44
[INFO] [stderr]    Compiling num-bigint v0.2.6
[INFO] [stderr]    Compiling num-complex v0.2.4
[INFO] [stderr]    Compiling num-rational v0.2.4
[INFO] [stderr]    Compiling num-iter v0.1.42
[INFO] [stderr]    Compiling indexmap v1.7.0
[INFO] [stderr]    Compiling tabular v0.1.4
[INFO] [stderr]    Compiling aho-corasick v0.7.18
[INFO] [stderr]    Compiling quote v1.0.9
[INFO] [stderr]    Compiling petgraph v0.5.1
[INFO] [stderr]    Compiling regex v1.5.4
[INFO] [stderr]    Compiling num v0.2.1
[INFO] [stderr]    Compiling parse_duration v2.1.1
[INFO] [stderr]    Compiling darling_core v0.10.2
[INFO] [stderr]    Compiling derive_more v0.99.16
[INFO] [stderr]    Compiling darling_macro v0.10.2
[INFO] [stderr]    Compiling darling v0.10.2
[INFO] [stderr]    Compiling boomerang_derive v0.1.0
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/boomerang_derive-0.1.0/src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(hash_set_entry)]
[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 `boomerang_derive` due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "4d3b092134f2553ea6c460109a4450c834b6dc5f0e01fc965bb42fe4e0d177b3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "4d3b092134f2553ea6c460109a4450c834b6dc5f0e01fc965bb42fe4e0d177b3", kill_on_drop: false }`
[INFO] [stdout] 4d3b092134f2553ea6c460109a4450c834b6dc5f0e01fc965bb42fe4e0d177b3