[INFO] fetching crate serde_cef 0.1.0...
[INFO] testing serde_cef-0.1.0 against beta-2020-07-24 for beta-1.46-1
[INFO] extracting crate serde_cef 0.1.0 into /workspace/builds/worker-0/source
[INFO] validating manifest of crates.io crate serde_cef 0.1.0 on toolchain beta-2020-07-24
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-07-24" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate serde_cef 0.1.0
[INFO] finished tweaking crates.io crate serde_cef 0.1.0
[INFO] tweaked toml for crates.io crate serde_cef 0.1.0 written to /workspace/builds/worker-0/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-07-24" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-07-24" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr] warning: only one of `license` or `license-file` is necessary
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded serde-value-flatten v0.1.0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env@sha256:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2020-07-24" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 772e3604f903c4f84392aa894f1c87cdd551c965d77063d376cd335f80da154f
[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" "772e3604f903c4f84392aa894f1c87cdd551c965d77063d376cd335f80da154f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "772e3604f903c4f84392aa894f1c87cdd551c965d77063d376cd335f80da154f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "772e3604f903c4f84392aa894f1c87cdd551c965d77063d376cd335f80da154f", kill_on_drop: false }`
[INFO] [stdout] 772e3604f903c4f84392aa894f1c87cdd551c965d77063d376cd335f80da154f
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env@sha256:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2020-07-24" "build" "--frozen" "--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] 2b1330fb0f1a9291070c2aedc846c1062419cf1388abe2f5b7ead2524d6c5465
[INFO] running `Command { std: "docker" "start" "-a" "2b1330fb0f1a9291070c2aedc846c1062419cf1388abe2f5b7ead2524d6c5465", kill_on_drop: false }`
[INFO] [stderr] warning: only one of `license` or `license-file` is necessary
[INFO] [stderr]    Compiling autocfg v1.0.0
[INFO] [stderr]    Compiling serde v1.0.114
[INFO] [stderr]    Compiling proc-macro2 v1.0.19
[INFO] [stderr]    Compiling memchr v2.3.3
[INFO] [stderr]    Compiling unicode-xid v0.2.1
[INFO] [stderr]    Compiling libc v0.2.74
[INFO] [stderr]    Compiling syn v1.0.37
[INFO] [stderr]    Compiling ryu v1.0.5
[INFO] [stderr]    Compiling serde_json v1.0.57
[INFO] [stderr]    Compiling lazy_static v1.4.0
[INFO] [stderr]    Compiling serde_derive v1.0.114
[INFO] [stderr]    Compiling itoa v0.4.6
[INFO] [stderr]    Compiling regex-syntax v0.6.18
[INFO] [stderr]    Compiling thread_local v1.0.1
[INFO] [stderr]    Compiling num-traits v0.2.12
[INFO] [stderr]    Compiling num-integer v0.1.43
[INFO] [stderr]    Compiling aho-corasick v0.7.13
[INFO] [stderr]    Compiling quote v1.0.7
[INFO] [stderr]    Compiling time v0.1.43
[INFO] [stderr]    Compiling ordered-float v1.1.0
[INFO] [stderr]    Compiling regex v1.3.9
[INFO] [stderr]    Compiling serde-value v0.6.0
[INFO] [stderr]    Compiling chrono v0.4.13
[INFO] [stderr]    Compiling serde-value-flatten v0.1.0
[INFO] [stderr]    Compiling serde_cef v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]   --> src/lib.rs:93:1
[INFO] [stdout]    |
[INFO] [stdout] 93 | #![feature(try_trait)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused imports: `Cursor`, `Write`
[INFO] [stdout]  --> src/ser.rs:1:15
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::io::{Cursor, Write};
[INFO] [stdout]   |               ^^^^^^  ^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error; 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `serde_cef`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "2b1330fb0f1a9291070c2aedc846c1062419cf1388abe2f5b7ead2524d6c5465", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2b1330fb0f1a9291070c2aedc846c1062419cf1388abe2f5b7ead2524d6c5465", kill_on_drop: false }`
[INFO] [stdout] 2b1330fb0f1a9291070c2aedc846c1062419cf1388abe2f5b7ead2524d6c5465