[INFO] fetching crate polymer 0.2.0...
[INFO] testing polymer-0.2.0 against 1.49.0 for beta-1.50-1
[INFO] extracting crate polymer 0.2.0 into /workspace/builds/worker-7/source
[INFO] validating manifest of crates.io crate polymer 0.2.0 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] removed /workspace/builds/worker-7/source/.cargo/config
[INFO] started tweaking crates.io crate polymer 0.2.0
[INFO] finished tweaking crates.io crate polymer 0.2.0
[INFO] tweaked toml for crates.io crate polymer 0.2.0 written to /workspace/builds/worker-7/source/Cargo.toml
[INFO] crate crates.io crate polymer 0.2.0 already has a lockfile, it will not be regenerated
[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] 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:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 2827b55832df2e75402540b5f01b03356dd649938df0b867dd5d20ff0f308b23
[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" "2827b55832df2e75402540b5f01b03356dd649938df0b867dd5d20ff0f308b23", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "2827b55832df2e75402540b5f01b03356dd649938df0b867dd5d20ff0f308b23", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2827b55832df2e75402540b5f01b03356dd649938df0b867dd5d20ff0f308b23", kill_on_drop: false }`
[INFO] [stdout] 2827b55832df2e75402540b5f01b03356dd649938df0b867dd5d20ff0f308b23
[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=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] 05b38cf9fe6f8ba57653910cb984814e2cb7fb909c6f453948eedc0e617cf1be
[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" "05b38cf9fe6f8ba57653910cb984814e2cb7fb909c6f453948eedc0e617cf1be", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.24
[INFO] [stderr]    Compiling unicode-xid v0.2.1
[INFO] [stderr]    Compiling syn v1.0.48
[INFO] [stderr]    Compiling typenum v1.12.0
[INFO] [stderr]    Compiling version_check v0.9.2
[INFO] [stderr]    Compiling semver-parser v0.7.0
[INFO] [stderr]    Compiling stable_deref_trait v1.2.0
[INFO] [stderr]    Compiling cortex-m v0.6.3
[INFO] [stderr]    Compiling vcell v0.1.2
[INFO] [stderr]    Compiling futures-core v0.3.7
[INFO] [stderr]    Compiling bitfield v0.13.2
[INFO] [stderr]    Compiling serde_derive v1.0.117
[INFO] [stderr]    Compiling futures-sink v0.3.7
[INFO] [stderr]    Compiling byteorder v1.3.4
[INFO] [stderr]    Compiling serde v1.0.117
[INFO] [stderr]    Compiling proc-macro2 v0.4.30
[INFO] [stderr]    Compiling pin-utils v0.1.0
[INFO] [stderr]    Compiling futures-task v0.3.7
[INFO] [stderr]    Compiling autocfg v1.0.1
[INFO] [stderr]    Compiling scopeguard v1.1.0
[INFO] [stderr]    Compiling futures-io v0.3.7
[INFO] [stderr]    Compiling unicode-xid v0.1.0
[INFO] [stderr]    Compiling heapless v0.5.6
[INFO] [stderr]    Compiling cortex-m-rt v0.6.13
[INFO] [stderr]    Compiling r0 v0.2.2
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling hashbrown v0.9.1
[INFO] [stderr]    Compiling cfg-if v0.1.10
[INFO] [stderr]    Compiling nb v1.0.0
[INFO] [stderr]    Compiling stm32f1 v0.11.0
[INFO] [stderr]    Compiling usb-device v0.2.7
[INFO] [stderr]    Compiling stm32-usbd v0.5.1
[INFO] [stderr]    Compiling void v1.0.2
[INFO] [stderr]    Compiling pin-project-internal v0.4.27
[INFO] [stderr]    Compiling log v0.4.11
[INFO] [stderr]    Compiling bytemuck v1.4.1
[INFO] [stderr]    Compiling rtic-core v0.3.0
[INFO] [stderr]    Compiling postcard-cobs v0.1.5-pre
[INFO] [stderr]    Compiling linked_list_allocator v0.8.6
[INFO] [stderr]    Compiling polymer v0.2.0 (/opt/rustwide/workdir)
[INFO] [stderr]    Compiling alloc-facade v0.5.0
[INFO] [stderr]    Compiling either v1.6.1
[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/linked_list_allocator-0.8.6/src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(const_mut_refs)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling panic-abort v0.3.2
[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 `linked_list_allocator`
[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] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/panic-abort-0.3.2/src/lib.rs:40:1
[INFO] [stdout]    |
[INFO] [stdout] 40 | #![feature(core_intrinsics)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[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/panic-abort-0.3.2/src/lib.rs:41:1
[INFO] [stdout]    |
[INFO] [stdout] 41 | #![feature(panic_handler)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 2 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "05b38cf9fe6f8ba57653910cb984814e2cb7fb909c6f453948eedc0e617cf1be", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "05b38cf9fe6f8ba57653910cb984814e2cb7fb909c6f453948eedc0e617cf1be", kill_on_drop: false }`
[INFO] [stdout] 05b38cf9fe6f8ba57653910cb984814e2cb7fb909c6f453948eedc0e617cf1be