[INFO] fetching crate iprs 0.0.4...
[INFO] testing iprs-0.0.4 against 1.49.0 for beta-1.50-1
[INFO] extracting crate iprs 0.0.4 into /workspace/builds/worker-2/source
[INFO] validating manifest of crates.io crate iprs 0.0.4 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 iprs 0.0.4
[INFO] finished tweaking crates.io crate iprs 0.0.4
[INFO] tweaked toml for crates.io crate iprs 0.0.4 written to /workspace/builds/worker-2/source/Cargo.toml
[INFO] crate crates.io crate iprs 0.0.4 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] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded bs58 v0.3.1
[INFO] [stderr]   Downloaded simplelog v0.7.6
[INFO] [stderr]   Downloaded ripemd160 v0.9.1
[INFO] [stderr]   Downloaded libsecp256k1 v0.3.5
[INFO] [stderr]   Downloaded structopt-derive v0.4.11
[INFO] [stderr]   Downloaded ripemd320 v0.9.0
[INFO] [stderr]   Downloaded pin-project v0.4.26
[INFO] [stderr]   Downloaded blake2s_simd v0.5.10
[INFO] [stderr]   Downloaded pin-project-internal v0.4.26
[INFO] [stderr]   Downloaded threefish-cipher v0.3.1
[INFO] [stderr]   Downloaded data-encoding-macro-internal v0.1.8
[INFO] [stderr]   Downloaded ed25519 v1.0.2
[INFO] [stderr]   Downloaded dns-lookup v1.0.4
[INFO] [stderr]   Downloaded k12 v0.1.0
[INFO] [stderr]   Downloaded asn1_der_derive v0.1.2
[INFO] [stderr]   Downloaded skein-hash v0.3.0
[INFO] [stderr]   Downloaded signature v1.2.2
[INFO] [stderr]   Downloaded parse_int v0.4.0
[INFO] [stderr]   Downloaded unsigned-varint v0.5.1
[INFO] [stderr]   Downloaded data-encoding-macro v0.1.8
[INFO] [stderr]   Downloaded structopt v0.3.18
[INFO] [stderr]   Downloaded md4 v0.9.0
[INFO] [stderr]   Downloaded asn1_der v0.6.3
[INFO] [stderr]   Downloaded ed25519-dalek v1.0.1
[INFO] [stderr]   Downloaded hmac-drbg v0.2.0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/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:c8ac004eab7d63a0ad09a2dde3d3353ba464f767bee4de425dc8f74c46a1905e" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "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] 6e628b49a3c7d0fd2b9be36028fbcee8d5402cc6ac73c78b0bc838e3498a02d3
[INFO] running `Command { std: "docker" "start" "-a" "6e628b49a3c7d0fd2b9be36028fbcee8d5402cc6ac73c78b0bc838e3498a02d3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "6e628b49a3c7d0fd2b9be36028fbcee8d5402cc6ac73c78b0bc838e3498a02d3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6e628b49a3c7d0fd2b9be36028fbcee8d5402cc6ac73c78b0bc838e3498a02d3", kill_on_drop: false }`
[INFO] [stdout] 6e628b49a3c7d0fd2b9be36028fbcee8d5402cc6ac73c78b0bc838e3498a02d3
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/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:c8ac004eab7d63a0ad09a2dde3d3353ba464f767bee4de425dc8f74c46a1905e" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] e6e459b3de302c6b9c088581a79f1cad6b9c5b7def4a8c7445753240dc0b957d
[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" "e6e459b3de302c6b9c088581a79f1cad6b9c5b7def4a8c7445753240dc0b957d", kill_on_drop: false }`
[INFO] [stderr]    Compiling typenum v1.12.0
[INFO] [stderr]    Compiling libc v0.2.79
[INFO] [stderr]    Compiling proc-macro2 v1.0.24
[INFO] [stderr]    Compiling syn v1.0.42
[INFO] [stderr]    Compiling version_check v0.9.2
[INFO] [stderr]    Compiling getrandom v0.1.15
[INFO] [stderr]    Compiling autocfg v1.0.1
[INFO] [stderr]    Compiling byteorder v1.3.4
[INFO] [stderr]    Compiling block-padding v0.2.1
[INFO] [stderr]    Compiling ppv-lite86 v0.2.9
[INFO] [stderr]    Compiling anyhow v1.0.33
[INFO] [stderr]    Compiling cc v1.0.60
[INFO] [stderr]    Compiling opaque-debug v0.3.0
[INFO] [stderr]    Compiling either v1.6.1
[INFO] [stderr]    Compiling hashbrown v0.9.1
[INFO] [stderr]    Compiling log v0.4.11
[INFO] [stderr]    Compiling subtle v2.3.0
[INFO] [stderr]    Compiling byte-tools v0.3.1
[INFO] [stderr]    Compiling remove_dir_all v0.5.3
[INFO] [stderr]    Compiling fixedbitset v0.2.0
[INFO] [stderr]    Compiling arrayref v0.3.6
[INFO] [stderr]    Compiling subtle v1.0.0
[INFO] [stderr]    Compiling unicode-segmentation v1.6.0
[INFO] [stderr]    Compiling multimap v0.8.2
[INFO] [stderr]    Compiling serde v1.0.116
[INFO] [stderr]    Compiling arrayvec v0.5.1
[INFO] [stderr]    Compiling maybe-uninit v2.0.0
[INFO] [stderr]    Compiling proc-macro-hack v0.5.18
[INFO] [stderr]    Compiling nix v0.17.0
[INFO] [stderr]    Compiling crunchy v0.2.2
[INFO] [stderr]    Compiling data-encoding v2.3.0
[INFO] [stderr]    Compiling cpuid-bool v0.1.2
[INFO] [stderr]    Compiling constant_time_eq v0.1.5
[INFO] [stderr]    Compiling signature v1.2.2
[INFO] [stderr]    Compiling opaque-debug v0.2.3
[INFO] [stderr]    Compiling fake-simd v0.1.2
[INFO] [stderr]    Compiling void v1.0.2
[INFO] [stderr]    Compiling base-x v0.2.6
[INFO] [stderr]    Compiling spin v0.5.2
[INFO] [stderr]    Compiling untrusted v0.7.1
[INFO] [stderr]    Compiling keccak v0.1.0
[INFO] [stderr]    Compiling bs58 v0.3.1
[INFO] [stderr]    Compiling unsigned-varint v0.5.1
[INFO] [stderr]    Compiling md5 v0.7.0
[INFO] [stderr]    Compiling itertools v0.8.2
[INFO] [stderr]    Compiling block-padding v0.1.5
[INFO] [stderr]    Compiling generic-array v0.14.4
[INFO] [stderr]    Compiling indexmap v1.6.0
[INFO] [stderr]    Compiling crossbeam-utils v0.7.2
[INFO] [stderr]    Compiling ed25519 v1.0.2
[INFO] [stderr]    Compiling heck v0.3.1
[INFO] [stderr]    Compiling blake2b_simd v0.5.10
[INFO] [stderr]    Compiling blake2s_simd v0.5.10
[INFO] [stderr]    Compiling quote v1.0.7
[INFO] [stderr]    Compiling ring v0.16.15
[INFO] [stderr]    Compiling blake3 v0.3.7
[INFO] [stderr]    Compiling generic-array v0.12.3
[INFO] [stderr]    Compiling petgraph v0.5.1
[INFO] [stderr]    Compiling crossbeam-channel v0.4.4
[INFO] [stderr]    Compiling digest v0.8.1
[INFO] [stderr]    Compiling block-buffer v0.7.3
[INFO] [stderr]    Compiling crypto-mac v0.7.0
[INFO] [stderr]    Compiling block-cipher-trait v0.6.2
[INFO] [stderr]    Compiling threefish-cipher v0.3.1
[INFO] [stderr]    Compiling hmac v0.7.1
[INFO] [stderr]    Compiling sha2 v0.8.2
[INFO] [stderr]    Compiling digest v0.9.0
[INFO] [stderr]    Compiling block-buffer v0.9.0
[INFO] [stderr]    Compiling crypto-mac v0.8.0
[INFO] [stderr]    Compiling hmac-drbg v0.2.0
[INFO] [stderr]    Compiling which v3.1.1
[INFO] [stderr]    Compiling socket2 v0.3.15
[INFO] [stderr]    Compiling skein-hash v0.3.0
[INFO] [stderr]    Compiling sha2 v0.9.1
[INFO] [stderr]    Compiling md4 v0.9.0
[INFO] [stderr]    Compiling ripemd160 v0.9.1
[INFO] [stderr]    Compiling sha-1 v0.9.1
[INFO] [stderr]    Compiling k12 v0.1.0
[INFO] [stderr]    Compiling sha3 v0.9.1
[INFO] [stderr]    Compiling ripemd320 v0.9.0
[INFO] [stderr]    Compiling rand_core v0.5.1
[INFO] [stderr]    Compiling dns-lookup v1.0.4
[INFO] [stderr]    Compiling prost-build v0.6.1
[INFO] [stderr]    Compiling rand_chacha v0.2.2
[INFO] [stderr]    Compiling rand v0.7.3
[INFO] [stderr]    Compiling tempfile v3.1.0
[INFO] [stderr]    Compiling libsecp256k1 v0.3.5
[INFO] [stderr]    Compiling ctrlc v3.1.6
[INFO] [stderr]    Compiling synstructure v0.12.4
[INFO] [stderr]    Compiling prost-derive v0.6.1
[INFO] [stderr]    Compiling zeroize_derive v1.0.1
[INFO] [stderr]    Compiling data-encoding-macro-internal v0.1.8
[INFO] [stderr]    Compiling asn1_der_derive v0.1.2
[INFO] [stderr]    Compiling asn1_der v0.6.3
[INFO] [stderr]    Compiling zeroize v1.1.1
[INFO] [stderr]    Compiling data-encoding-macro v0.1.8
[INFO] [stderr]    Compiling curve25519-dalek v3.0.0
[INFO] [stderr]    Compiling multibase v0.8.0
[INFO] [stderr]    Compiling ed25519-dalek v1.0.1
[INFO] [stderr]    Compiling prost v0.6.1
[INFO] [stderr]    Compiling prost-types v0.6.1
[INFO] [stderr]    Compiling iprs v0.0.4 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> src/lib.rs:12:1
[INFO] [stdout]    |
[INFO] [stdout] 12 | #![feature(box_syntax, box_patterns)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[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 `iprs`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "e6e459b3de302c6b9c088581a79f1cad6b9c5b7def4a8c7445753240dc0b957d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e6e459b3de302c6b9c088581a79f1cad6b9c5b7def4a8c7445753240dc0b957d", kill_on_drop: false }`
[INFO] [stdout] e6e459b3de302c6b9c088581a79f1cad6b9c5b7def4a8c7445753240dc0b957d