[INFO] crate slice 0.0.4 is already in cache
[INFO] extracting crate slice 0.0.4 into work/ex/beta-1.37-6/sources/1.36.0/reg/slice/0.0.4
[INFO] extracting crate slice 0.0.4 into work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/slice/0.0.4
[INFO] validating manifest of slice-0.0.4 on toolchain 1.36.0
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of slice-0.0.4 on toolchain beta-2019-07-23
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing slice-0.0.4
[INFO] finished frobbing slice-0.0.4
[INFO] frobbed toml for slice-0.0.4 written to work/ex/beta-1.37-6/sources/1.36.0/reg/slice/0.0.4/Cargo.toml
[INFO] started frobbing slice-0.0.4
[INFO] finished frobbing slice-0.0.4
[INFO] frobbed toml for slice-0.0.4 written to work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/slice/0.0.4/Cargo.toml
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] testing slice-0.0.4 against beta-2019-07-23 for beta-1.37-6
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.37-6/worker-3/beta-2019-07-23:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/slice/0.0.4:/opt/crater/workdir:ro,Z" "-v" "/mnt/big/crater/work/local/cargo-home:/opt/crater/cargo-home:ro,Z" "-v" "/mnt/big/crater/work/local/rustup-home:/opt/crater/rustup-home:ro,Z" "-e" "USER_ID=1000" "-e" "SOURCE_DIR=/opt/crater/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/crater/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/crater/cargo-home" "-e" "RUSTUP_HOME=/opt/crater/rustup-home" "-w" "/opt/crater/workdir" "-m" "1536M" "--network" "none" "rustops/crates-build-env" "/opt/crater/cargo-home/bin/cargo" "+beta-2019-07-23" "build" "--frozen"`
[INFO] [stdout] 1b9ec87cafdb955e9177e4b013f44572b6eb1d6ff97f828bddf1032e34f62637
[INFO] running `"docker" "start" "-a" "1b9ec87cafdb955e9177e4b013f44572b6eb1d6ff97f828bddf1032e34f62637"`
[INFO] [stderr]    Compiling slice v0.0.4 (/opt/crater/workdir)
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.40s
[INFO] running `"docker" "inspect" "1b9ec87cafdb955e9177e4b013f44572b6eb1d6ff97f828bddf1032e34f62637"`
[INFO] running `"docker" "rm" "-f" "1b9ec87cafdb955e9177e4b013f44572b6eb1d6ff97f828bddf1032e34f62637"`
[INFO] [stdout] 1b9ec87cafdb955e9177e4b013f44572b6eb1d6ff97f828bddf1032e34f62637
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.37-6/worker-3/beta-2019-07-23:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/slice/0.0.4:/opt/crater/workdir:ro,Z" "-v" "/mnt/big/crater/work/local/cargo-home:/opt/crater/cargo-home:ro,Z" "-v" "/mnt/big/crater/work/local/rustup-home:/opt/crater/rustup-home:ro,Z" "-e" "USER_ID=1000" "-e" "SOURCE_DIR=/opt/crater/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/crater/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/crater/cargo-home" "-e" "RUSTUP_HOME=/opt/crater/rustup-home" "-w" "/opt/crater/workdir" "-m" "1536M" "--network" "none" "rustops/crates-build-env" "/opt/crater/cargo-home/bin/cargo" "+beta-2019-07-23" "test" "--frozen" "--no-run"`
[INFO] [stdout] ad30d72cfd153e8139dec35c62dd169ccb1d6611c338858a4468d1d7f2c077d1
[INFO] running `"docker" "start" "-a" "ad30d72cfd153e8139dec35c62dd169ccb1d6611c338858a4468d1d7f2c077d1"`
[INFO] [stderr]    Compiling slice v0.0.4 (/opt/crater/workdir)
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.80s
[INFO] running `"docker" "inspect" "ad30d72cfd153e8139dec35c62dd169ccb1d6611c338858a4468d1d7f2c077d1"`
[INFO] running `"docker" "rm" "-f" "ad30d72cfd153e8139dec35c62dd169ccb1d6611c338858a4468d1d7f2c077d1"`
[INFO] [stdout] ad30d72cfd153e8139dec35c62dd169ccb1d6611c338858a4468d1d7f2c077d1
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.37-6/worker-3/beta-2019-07-23:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/slice/0.0.4:/opt/crater/workdir:ro,Z" "-v" "/mnt/big/crater/work/local/cargo-home:/opt/crater/cargo-home:ro,Z" "-v" "/mnt/big/crater/work/local/rustup-home:/opt/crater/rustup-home:ro,Z" "-e" "USER_ID=1000" "-e" "SOURCE_DIR=/opt/crater/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/crater/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/crater/cargo-home" "-e" "RUSTUP_HOME=/opt/crater/rustup-home" "-w" "/opt/crater/workdir" "-m" "1536M" "--network" "none" "rustops/crates-build-env" "/opt/crater/cargo-home/bin/cargo" "+beta-2019-07-23" "test" "--frozen"`
[INFO] [stdout] 4ac544f74120ef0f58b88bb4c6f23e04d489089ca9c4fdaf28f65eaeeb21e319
[INFO] running `"docker" "start" "-a" "4ac544f74120ef0f58b88bb4c6f23e04d489089ca9c4fdaf28f65eaeeb21e319"`
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.01s
[INFO] [stderr]      Running /opt/crater/target/debug/deps/slice-b1d3f78dcfb4748a
[INFO] [stderr]    Doc-tests slice
[INFO] [stdout] 
[INFO] [stdout] running 0 tests
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] running 2 tests
[INFO] [stdout] test src/lib.rs -  (line 10) ... FAILED
[INFO] [stdout] test src/lib.rs - IoSlice (line 56) ... FAILED
[INFO] [stderr] error: test failed, to rerun pass '--doc'
[INFO] [stdout] 
[INFO] [stdout] failures:
[INFO] [stdout] 
[INFO] [stdout] ---- src/lib.rs -  (line 10) stdout ----
[INFO] [stdout] error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `std::ops::Try`)
[INFO] [stdout]  --> src/lib.rs:14:14
[INFO] [stdout]   |
[INFO] [stdout] 7 | let source = File::open("/home/annie/data.png")?;
[INFO] [stdout]   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot use the `?` operator in a function that returns `()`
[INFO] [stdout]   |
[INFO] [stdout]   = help: the trait `std::ops::Try` is not implemented for `()`
[INFO] [stdout]   = note: required by `std::ops::Try::from_error`
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0277`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] ---- src/lib.rs - IoSlice (line 56) stdout ----
[INFO] [stdout] error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `std::ops::Try`)
[INFO] [stdout]  --> src/lib.rs:60:14
[INFO] [stdout]   |
[INFO] [stdout] 7 | let source = File::open("/home/annie/data.png")?;
[INFO] [stdout]   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot use the `?` operator in a function that returns `()`
[INFO] [stdout]   |
[INFO] [stdout]   = help: the trait `std::ops::Try` is not implemented for `()`
[INFO] [stdout]   = note: required by `std::ops::Try::from_error`
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0277`.
[INFO] [stdout] Couldn't compile the test.
[INFO] [stdout] 
[INFO] [stdout] failures:
[INFO] [stdout]     src/lib.rs -  (line 10)
[INFO] [stdout]     src/lib.rs - IoSlice (line 56)
[INFO] [stdout] 
[INFO] [stdout] test result: FAILED. 0 passed; 2 failed; 0 ignored; 0 measured; 0 filtered out
[INFO] [stdout] 
[INFO] running `"docker" "inspect" "4ac544f74120ef0f58b88bb4c6f23e04d489089ca9c4fdaf28f65eaeeb21e319"`
[INFO] running `"docker" "rm" "-f" "4ac544f74120ef0f58b88bb4c6f23e04d489089ca9c4fdaf28f65eaeeb21e319"`
[INFO] [stdout] 4ac544f74120ef0f58b88bb4c6f23e04d489089ca9c4fdaf28f65eaeeb21e319