[INFO] fetching crate maybe-serde 0.2.1...
[INFO] checking maybe-serde-0.2.1 against master#db870ea71b6dcc7a91b999420b88f41d3cdd13e1 for pr-75192
[INFO] extracting crate maybe-serde 0.2.1 into /workspace/builds/worker-7/source
[INFO] validating manifest of crates.io crate maybe-serde 0.2.1 on toolchain db870ea71b6dcc7a91b999420b88f41d3cdd13e1
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+db870ea71b6dcc7a91b999420b88f41d3cdd13e1" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate maybe-serde 0.2.1
[INFO] finished tweaking crates.io crate maybe-serde 0.2.1
[INFO] tweaked toml for crates.io crate maybe-serde 0.2.1 written to /workspace/builds/worker-7/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+db870ea71b6dcc7a91b999420b88f41d3cdd13e1" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+db870ea71b6dcc7a91b999420b88f41d3cdd13e1" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/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:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+db870ea71b6dcc7a91b999420b88f41d3cdd13e1" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] fe7944d015d4a2738b6533abebb3dc2759f9879f8cd4884387862e9637295bed
[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" "fe7944d015d4a2738b6533abebb3dc2759f9879f8cd4884387862e9637295bed", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "fe7944d015d4a2738b6533abebb3dc2759f9879f8cd4884387862e9637295bed", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "fe7944d015d4a2738b6533abebb3dc2759f9879f8cd4884387862e9637295bed", kill_on_drop: false }`
[INFO] [stdout] fe7944d015d4a2738b6533abebb3dc2759f9879f8cd4884387862e9637295bed
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/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:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+db870ea71b6dcc7a91b999420b88f41d3cdd13e1" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] c20ca61158d47298ce51dbd70ec8f35fc235b4bb8a2102e6a59987ff4aeb3237
[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" "c20ca61158d47298ce51dbd70ec8f35fc235b4bb8a2102e6a59987ff4aeb3237", kill_on_drop: false }`
[INFO] [stderr]     Checking itoa v0.4.6
[INFO] [stderr]     Checking maybe-serde v0.2.1 (/opt/rustwide/workdir)
[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:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![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] 
[INFO] [stdout] 
[INFO] [stderr]     Checking serde_json v1.0.57
[INFO] [stdout] warning: 1 warning emitted
[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:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![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] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 2.55s
[INFO] running `Command { std: "docker" "inspect" "c20ca61158d47298ce51dbd70ec8f35fc235b4bb8a2102e6a59987ff4aeb3237", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c20ca61158d47298ce51dbd70ec8f35fc235b4bb8a2102e6a59987ff4aeb3237", kill_on_drop: false }`
[INFO] [stdout] c20ca61158d47298ce51dbd70ec8f35fc235b4bb8a2102e6a59987ff4aeb3237