[INFO] updating cached repository tolae/RustOS
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/tolae/RustOS
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/tolae/RustOS" "work/ex/beta-1.38-1/sources/1.37.0/gh/tolae/RustOS"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/tolae/RustOS'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/tolae/RustOS" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/tolae/RustOS"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/tolae/RustOS'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] b6095d44db18c00ab8c2b048b3f68073158a2380
[INFO] sha for GitHub repo tolae/RustOS: b6095d44db18c00ab8c2b048b3f68073158a2380
[INFO] validating manifest of tolae/RustOS 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 tolae/RustOS 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 tolae/RustOS
[INFO] finished frobbing tolae/RustOS
[INFO] frobbed toml for tolae/RustOS written to work/ex/beta-1.38-1/sources/1.37.0/gh/tolae/RustOS/Cargo.toml
[INFO] started frobbing tolae/RustOS
[INFO] finished frobbing tolae/RustOS
[INFO] frobbed toml for tolae/RustOS written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/tolae/RustOS/Cargo.toml
[INFO] crate tolae/RustOS 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 download `bootloader v0.4.0`
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   unable to get packages from source
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   failed to parse manifest at `/mnt/big/crater/work/local/cargo-home/registry/src/github.com-1ecc6299db9ec823/bootloader-0.4.0/Cargo.toml`
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   the cargo feature `publish-lockfile` requires a nightly version of Cargo, but this is the `stable` channel
[INFO] [stderr] See https://doc.rust-lang.org/book/appendix-07-nightly-rust.html for more information about Rust release channels.
[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