[INFO] updating cached repository https://github.com/rust-lang-nursery/polonius
[INFO] running `"git" "-c" "credential.helper=" "-c" "credential.helper=/big/crater/work/cargo-home/bin/git-credential-null" "-c" "remote.origin.fetch=refs/heads/*:refs/heads/*" "fetch" "origin" "--force" "--prune"`
[INFO] [stderr] From https://github.com/rust-lang-nursery/polonius
[INFO] [stderr]  + 1eaf5f64e2...1c9e800f4d gh-pages   -> gh-pages  (forced update)
[INFO] [stderr]    a05aea44d9..1f31a28d86  master     -> master
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 1f31a28d86f4b2768a8c64d763344ff8838dd130
[ERROR] this task or one of its parent failed!
[ERROR] command `"/big/crater/work/cargo-home/bin/cargo" "+1.38.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"` failed
[ERROR] note: run with `RUST_BACKTRACE=1` to display a backtrace.