[INFO] updating cached repository Linesmerrill/hero-api
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/Linesmerrill/hero-api
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/Linesmerrill/hero-api" "work/ex/beta-1.38-1/sources/1.37.0/gh/Linesmerrill/hero-api"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/Linesmerrill/hero-api'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/Linesmerrill/hero-api" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/Linesmerrill/hero-api"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/Linesmerrill/hero-api'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 6212c524a55deafec658e3d83c70b3ba6fc36cac
[INFO] sha for GitHub repo Linesmerrill/hero-api: 6212c524a55deafec658e3d83c70b3ba6fc36cac
[INFO] validating manifest of Linesmerrill/hero-api on toolchain 1.37.0
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of Linesmerrill/hero-api on toolchain beta-2019-08-13
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing Linesmerrill/hero-api
[INFO] finished frobbing Linesmerrill/hero-api
[INFO] frobbed toml for Linesmerrill/hero-api written to work/ex/beta-1.38-1/sources/1.37.0/gh/Linesmerrill/hero-api/Cargo.toml
[INFO] started frobbing Linesmerrill/hero-api
[INFO] finished frobbing Linesmerrill/hero-api
[INFO] frobbed toml for Linesmerrill/hero-api written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/Linesmerrill/hero-api/Cargo.toml
[INFO] crate Linesmerrill/hero-api already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] [stderr] error: failed to parse lock file at: /mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/gh/Linesmerrill/hero-api/Cargo.lock
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   package `serde_derive` is specified twice in the lockfile
[ERROR] this task or one of its parent failed!
[ERROR] command `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"` failed