[INFO] fetching crate mamba 0.3.0...
[INFO] testing mamba-0.3.0 against 1.55.0 for beta-1.56-1
[INFO] extracting crate mamba 0.3.0 into /workspace/builds/worker-14/source
[INFO] validating manifest of crates.io crate mamba 0.3.0 on toolchain 1.55.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate mamba 0.3.0
[INFO] finished tweaking crates.io crate mamba 0.3.0
[INFO] tweaked toml for crates.io crate mamba 0.3.0 written to /workspace/builds/worker-14/source/Cargo.toml
[INFO] crate crates.io crate mamba 0.3.0 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "metadata" "--no-deps" "--format-version=1", 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] 50ced9d50e98d161f33f22edabc0c92a6ec98aef8ba36466dc7efb6a4a1ec188
[INFO] running `Command { std: "docker" "start" "-a" "50ced9d50e98d161f33f22edabc0c92a6ec98aef8ba36466dc7efb6a4a1ec188", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "50ced9d50e98d161f33f22edabc0c92a6ec98aef8ba36466dc7efb6a4a1ec188", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "50ced9d50e98d161f33f22edabc0c92a6ec98aef8ba36466dc7efb6a4a1ec188", kill_on_drop: false }`
[INFO] [stdout] 50ced9d50e98d161f33f22edabc0c92a6ec98aef8ba36466dc7efb6a4a1ec188
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 7ba337afe86d06f67f73ea3a66fc56c42da4629da720b2b648e9215cb045897b
[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" "7ba337afe86d06f67f73ea3a66fc56c42da4629da720b2b648e9215cb045897b", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.7
[INFO] [stderr]    Compiling syn v1.0.13
[INFO] [stderr]    Compiling bytecount v0.3.2
[INFO] [stderr]    Compiling wtf8 v0.0.3
[INFO] [stderr]    Compiling unicode_names2 v0.2.2
[INFO] [stderr]    Compiling pathdiff v0.1.0
[INFO] [stderr]    Compiling num-traits v0.2.10
[INFO] [stderr]    Compiling num-integer v0.1.41
[INFO] [stderr]    Compiling num-bigint v0.2.4
[INFO] [stderr]    Compiling predicates v1.0.2
[INFO] [stderr]    Compiling getrandom v0.1.14
[INFO] [stderr]    Compiling nom v4.2.3
[INFO] [stderr]    Compiling clap v2.33.0
[INFO] [stderr]    Compiling loggerv v0.7.2
[INFO] [stderr]    Compiling rand_core v0.5.1
[INFO] [stderr]    Compiling rand_chacha v0.2.1
[INFO] [stderr]    Compiling rand v0.7.3
[INFO] [stderr]    Compiling nom_locate v0.3.1
[INFO] [stderr]    Compiling quote v1.0.2
[INFO] [stderr]    Compiling tempfile v3.1.0
[INFO] [stderr]    Compiling python-parser v0.1.0
[INFO] [stderr]    Compiling serde_derive v1.0.104
[INFO] [stderr]    Compiling serde v1.0.104
[INFO] [stderr]    Compiling serde_json v1.0.44
[INFO] [stderr]    Compiling escargot v0.3.1
[INFO] [stderr]    Compiling assert_cmd v0.10.2
[INFO] [stderr]    Compiling mamba v0.3.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(drain_filter)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary trailing semicolon
[INFO] [stdout]   --> src/check/constrain/unify/expression/substitute.rs:33:10
[INFO] [stdout]    |
[INFO] [stdout] 33 |         };
[INFO] [stdout]    |          ^ help: remove this semicolon
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(redundant_semicolons)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary parentheses around block return value
[INFO] [stdout]    --> src/lex/token.rs:139:9
[INFO] [stdout]     |
[INFO] [stdout] 139 | /         (match self {
[INFO] [stdout] 140 | |             Token::Id(id) => id.len(),
[INFO] [stdout] 141 | |             Token::Real(real) => real.len(),
[INFO] [stdout] 142 | |             Token::Int(int) => int.len(),
[INFO] [stdout] ...   |
[INFO] [stdout] 148 | |             other => format!("{}", other).len()
[INFO] [stdout] 149 | |         } as i32)
[INFO] [stdout]     | |_________________^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_parens)]` on by default
[INFO] [stdout] help: remove these parentheses
[INFO] [stdout]     |
[INFO] [stdout] 139 |         match self {
[INFO] [stdout] 140 |             Token::Id(id) => id.len(),
[INFO] [stdout] 141 |             Token::Real(real) => real.len(),
[INFO] [stdout] 142 |             Token::Int(int) => int.len(),
[INFO] [stdout] 143 |             Token::Bool(true) => 4,
[INFO] [stdout] 144 |             Token::Bool(false) => 5,
[INFO] [stdout]   ...
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary trailing semicolon
[INFO] [stdout]   --> src/parse/definition.rs:25:6
[INFO] [stdout]    |
[INFO] [stdout] 25 |     };
[INFO] [stdout]    |      ^ help: remove this semicolon
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error; 3 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 `mamba` due to 2 previous errors; 3 warnings emitted
[INFO] running `Command { std: "docker" "inspect" "7ba337afe86d06f67f73ea3a66fc56c42da4629da720b2b648e9215cb045897b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7ba337afe86d06f67f73ea3a66fc56c42da4629da720b2b648e9215cb045897b", kill_on_drop: false }`
[INFO] [stdout] 7ba337afe86d06f67f73ea3a66fc56c42da4629da720b2b648e9215cb045897b