[INFO] fetching crate jsonwebkey 0.2.0...
[INFO] testing jsonwebkey-0.2.0 against 1.49.0 for beta-1.50-1
[INFO] extracting crate jsonwebkey 0.2.0 into /workspace/builds/worker-4/source
[INFO] validating manifest of crates.io crate jsonwebkey 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] started tweaking crates.io crate jsonwebkey 0.2.0
[INFO] finished tweaking crates.io crate jsonwebkey 0.2.0
[INFO] tweaked toml for crates.io crate jsonwebkey 0.2.0 written to /workspace/builds/worker-4/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] 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" "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] c3e359b825cbf7faab27e148dafa4174b88a7f73ef3ce4601b7479e6d1b8de3a
[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" "c3e359b825cbf7faab27e148dafa4174b88a7f73ef3ce4601b7479e6d1b8de3a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "c3e359b825cbf7faab27e148dafa4174b88a7f73ef3ce4601b7479e6d1b8de3a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c3e359b825cbf7faab27e148dafa4174b88a7f73ef3ce4601b7479e6d1b8de3a", kill_on_drop: false }`
[INFO] [stdout] c3e359b825cbf7faab27e148dafa4174b88a7f73ef3ce4601b7479e6d1b8de3a
[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=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] c5e5f54d9cd61ad39b787799c2e1e4dd44d9709709e1d803d8cfcb8b49e1b587
[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" "c5e5f54d9cd61ad39b787799c2e1e4dd44d9709709e1d803d8cfcb8b49e1b587", kill_on_drop: false }`
[INFO] [stderr]    Compiling derive_more v0.99.11
[INFO] [stderr]    Compiling zeroize_derive v1.0.1
[INFO] [stderr]    Compiling zeroize v1.2.0
[INFO] [stderr]    Compiling jsonwebkey v0.2.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(box_syntax, const_generics, fixed_size_array)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: a method with this name may be added to the standard library in the future
[INFO] [stdout]   --> src/byte_array.rs:20:51
[INFO] [stdout]    |
[INFO] [stdout] 20 |             write!(f, "{}", base64::encode(self.0.as_slice()))
[INFO] [stdout]    |                                                   ^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unstable_name_collisions)]` on by default
[INFO] [stdout]    = warning: once this method is added to the standard library, the ambiguity may cause an error or change in behavior!
[INFO] [stdout]    = note: for more information, see issue #48919 <https://github.com/rust-lang/rust/issues/48919>
[INFO] [stdout]    = help: call with fully qualified syntax `as_slice(...)` to keep using the current method
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: a method with this name may be added to the standard library in the future
[INFO] [stdout]   --> src/byte_array.rs:29:16
[INFO] [stdout]    |
[INFO] [stdout] 29 |         self.0.as_slice() == other.0.as_slice()
[INFO] [stdout]    |                ^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: once this method is added to the standard library, the ambiguity may cause an error or change in behavior!
[INFO] [stdout]    = note: for more information, see issue #48919 <https://github.com/rust-lang/rust/issues/48919>
[INFO] [stdout]    = help: call with fully qualified syntax `as_slice(...)` to keep using the current method
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: a method with this name may be added to the standard library in the future
[INFO] [stdout]   --> src/byte_array.rs:29:38
[INFO] [stdout]    |
[INFO] [stdout] 29 |         self.0.as_slice() == other.0.as_slice()
[INFO] [stdout]    |                                      ^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: once this method is added to the standard library, the ambiguity may cause an error or change in behavior!
[INFO] [stdout]    = note: for more information, see issue #48919 <https://github.com/rust-lang/rust/issues/48919>
[INFO] [stdout]    = help: call with fully qualified syntax `as_slice(...)` to keep using the current method
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: a method with this name may be added to the standard library in the future
[INFO] [stdout]   --> src/byte_array.rs:50:33
[INFO] [stdout]    |
[INFO] [stdout] 50 |         serialize_base64(self.0.as_slice(), s)
[INFO] [stdout]    |                                 ^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: once this method is added to the standard library, the ambiguity may cause an error or change in behavior!
[INFO] [stdout]    = note: for more information, see issue #48919 <https://github.com/rust-lang/rust/issues/48919>
[INFO] [stdout]    = help: call with fully qualified syntax `as_slice(...)` to keep using the current method
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error; 4 warnings 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 `jsonwebkey`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "c5e5f54d9cd61ad39b787799c2e1e4dd44d9709709e1d803d8cfcb8b49e1b587", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c5e5f54d9cd61ad39b787799c2e1e4dd44d9709709e1d803d8cfcb8b49e1b587", kill_on_drop: false }`
[INFO] [stdout] c5e5f54d9cd61ad39b787799c2e1e4dd44d9709709e1d803d8cfcb8b49e1b587