[INFO] cloning repository https://github.com/cowang4/S4h
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/cowang4/S4h" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fcowang4%2FS4h", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fcowang4%2FS4h'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 842c93a0ffe94c4e6cbcf041cfcaad39dfd82d76
[INFO] checking cowang4/S4h against master#a42d94ebb883116f2867cbe3016d9bde9ca6d3f7 for pr-117593
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fcowang4%2FS4h" "/workspace/builds/worker-5-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-5-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/cowang4/S4h on toolchain a42d94ebb883116f2867cbe3016d9bde9ca6d3f7
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+a42d94ebb883116f2867cbe3016d9bde9ca6d3f7" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/cowang4/S4h
[INFO] finished tweaking git repo https://github.com/cowang4/S4h
[INFO] tweaked toml for git repo https://github.com/cowang4/S4h written to /workspace/builds/worker-5-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/cowang4/S4h already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+a42d94ebb883116f2867cbe3016d9bde9ca6d3f7" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr] error: failed to select a version for `serde_derive`.
[INFO] [stderr]     ... required by package `serde v1.0.188`
[INFO] [stderr]     ... which satisfies dependency `serde = "^1"` (locked to 1.0.188) of package `s4h v0.2.0 (/workspace/builds/worker-5-tc1/source)`
[INFO] [stderr] versions that meet the requirements `=1.0.188` are: 1.0.188
[INFO] [stderr] 
[INFO] [stderr] all possible versions conflict with previously selected packages.
[INFO] [stderr] 
[INFO] [stderr]   previously selected package `serde_derive v1.0.186`
[INFO] [stderr]     ... which satisfies dependency `serde_derive = "^1"` (locked to 1.0.186) of package `s4h v0.2.0 (/workspace/builds/worker-5-tc1/source)`
[INFO] [stderr] 
[INFO] [stderr] failed to select a version for `serde_derive` which could resolve this conflict
[ERROR] this task or one of its parent failed!
[ERROR] command failed: exit status: 101
[ERROR] note: run with `RUST_BACKTRACE=1` to display a backtrace.