[INFO] fetching crate back-to-the-future 0.1.7...
[INFO] checking back-to-the-future-0.1.7 against master#836c31742687ba4e2f857b5b698e1e9e6b67619c for pr-81789
[INFO] extracting crate back-to-the-future 0.1.7 into /workspace/builds/worker-4/source
[INFO] validating manifest of crates.io crate back-to-the-future 0.1.7 on toolchain 836c31742687ba4e2f857b5b698e1e9e6b67619c
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+836c31742687ba4e2f857b5b698e1e9e6b67619c" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate back-to-the-future 0.1.7
[INFO] finished tweaking crates.io crate back-to-the-future 0.1.7
[INFO] tweaked toml for crates.io crate back-to-the-future 0.1.7 written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+836c31742687ba4e2f857b5b698e1e9e6b67619c" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+836c31742687ba4e2f857b5b698e1e9e6b67619c" "fetch" "--locked" "--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-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+836c31742687ba4e2f857b5b698e1e9e6b67619c" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] a0db980e9b3e666372b965c7d45293b4f3ba280eea4ba14d8b35228e1c6e196c
[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" "a0db980e9b3e666372b965c7d45293b4f3ba280eea4ba14d8b35228e1c6e196c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "a0db980e9b3e666372b965c7d45293b4f3ba280eea4ba14d8b35228e1c6e196c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a0db980e9b3e666372b965c7d45293b4f3ba280eea4ba14d8b35228e1c6e196c", kill_on_drop: false }`
[INFO] [stdout] a0db980e9b3e666372b965c7d45293b4f3ba280eea4ba14d8b35228e1c6e196c
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+836c31742687ba4e2f857b5b698e1e9e6b67619c" "check" "--frozen" "--all" "--all-targets" "--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] 89de8178034f0bb9e82f5e2186214d844abcf25d01e13193e7f2d76c7bcaf521
[INFO] running `Command { std: "docker" "start" "-a" "89de8178034f0bb9e82f5e2186214d844abcf25d01e13193e7f2d76c7bcaf521", kill_on_drop: false }`
[INFO] [stderr]     Checking back-to-the-future v0.1.7 (/opt/rustwide/workdir)
[INFO] [stderr]     Checking bytes v0.4.12
[INFO] [stdout] error[E0557]: feature has been removed
[INFO] [stdout]   --> src/lib.rs:36:12
[INFO] [stdout]    |
[INFO] [stdout] 36 | #![feature(await_macro)]
[INFO] [stdout]    |            ^^^^^^^^^^^ feature has been removed
[INFO] [stdout]    |
[INFO] [stdout]    = note: subsumed by `.await` syntax
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
[INFO] [stdout]   --> src/lib.rs:40:12
[INFO] [stdout]    |
[INFO] [stdout] 40 | #![feature(specialization)]
[INFO] [stdout]    |            ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(incomplete_features)]` on by default
[INFO] [stdout]    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
[INFO] [stdout]    = help: consider using `min_specialization` instead, which is more stable and complete
[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 E0557`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `back-to-the-future`
[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" "89de8178034f0bb9e82f5e2186214d844abcf25d01e13193e7f2d76c7bcaf521", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "89de8178034f0bb9e82f5e2186214d844abcf25d01e13193e7f2d76c7bcaf521", kill_on_drop: false }`
[INFO] [stdout] 89de8178034f0bb9e82f5e2186214d844abcf25d01e13193e7f2d76c7bcaf521