[INFO] fetching crate boomerang 0.1.0...
[INFO] testing boomerang-0.1.0 against 1.49.0 for beta-1.50-1
[INFO] extracting crate boomerang 0.1.0 into /workspace/builds/worker-2/source
[INFO] validating manifest of crates.io crate boomerang 0.1.0 on toolchain 1.49.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "read-manifest" "--manifest-path" "Cargo.toml", 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-2/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[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:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 2fe6a99870faa572a3c23ad5f841491737589e2af99b6a5bcf3af52a6ee5e9a2
[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" "2fe6a99870faa572a3c23ad5f841491737589e2af99b6a5bcf3af52a6ee5e9a2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "2fe6a99870faa572a3c23ad5f841491737589e2af99b6a5bcf3af52a6ee5e9a2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2fe6a99870faa572a3c23ad5f841491737589e2af99b6a5bcf3af52a6ee5e9a2", kill_on_drop: false }`
[INFO] [stdout] 2fe6a99870faa572a3c23ad5f841491737589e2af99b6a5bcf3af52a6ee5e9a2
[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=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:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] b02aaa32a4de103ebc5a8e23dc250c7b0afdfd996ee4ccb3d329523d69141f39
[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" "b02aaa32a4de103ebc5a8e23dc250c7b0afdfd996ee4ccb3d329523d69141f39", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.24
[INFO] [stderr]    Compiling unicode-xid v0.2.1
[INFO] [stderr]    Compiling syn v1.0.57
[INFO] [stderr]    Compiling memchr v2.3.4
[INFO] [stderr]    Compiling ident_case v1.0.1
[INFO] [stderr]    Compiling strsim v0.9.3
[INFO] [stderr]    Compiling fnv v1.0.7
[INFO] [stderr]    Compiling lazy_static v1.4.0
[INFO] [stderr]    Compiling hashbrown v0.9.1
[INFO] [stderr]    Compiling regex-syntax v0.6.21
[INFO] [stderr]    Compiling fixedbitset v0.2.0
[INFO] [stderr]    Compiling unicode-width v0.1.8
[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 v1.6.1
[INFO] [stderr]    Compiling thread_local v1.0.1
[INFO] [stderr]    Compiling tabular v0.1.4
[INFO] [stderr]    Compiling aho-corasick v0.7.15
[INFO] [stderr]    Compiling quote v1.0.8
[INFO] [stderr]    Compiling petgraph v0.5.1
[INFO] [stderr]    Compiling regex v1.4.2
[INFO] [stderr]    Compiling num v0.2.1
[INFO] [stderr]    Compiling parse_duration v2.1.0
[INFO] [stderr]    Compiling darling_core v0.10.2
[INFO] [stderr]    Compiling derive_more v0.99.11
[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`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "b02aaa32a4de103ebc5a8e23dc250c7b0afdfd996ee4ccb3d329523d69141f39", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b02aaa32a4de103ebc5a8e23dc250c7b0afdfd996ee4ccb3d329523d69141f39", kill_on_drop: false }`
[INFO] [stdout] b02aaa32a4de103ebc5a8e23dc250c7b0afdfd996ee4ccb3d329523d69141f39