[INFO] fetching crate bui-backend 0.6.0...
[INFO] extracting crate bui-backend 0.6.0 into work/ex/pr-58899/sources/master#c0086b9e8972fef9fd4af24bae20d45021ed06c6/reg/bui-backend/0.6.0
[INFO] extracting crate bui-backend 0.6.0 into work/ex/pr-58899/sources/try#290ac7b29f41ff9fa5232f9a1116ea71a3501063/reg/bui-backend/0.6.0
[INFO] validating manifest of bui-backend-0.6.0 on toolchain master#c0086b9e8972fef9fd4af24bae20d45021ed06c6
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+c0086b9e8972fef9fd4af24bae20d45021ed06c6-alt" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of bui-backend-0.6.0 on toolchain try#290ac7b29f41ff9fa5232f9a1116ea71a3501063
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+290ac7b29f41ff9fa5232f9a1116ea71a3501063-alt" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing bui-backend-0.6.0
[INFO] finished frobbing bui-backend-0.6.0
[INFO] frobbed toml for bui-backend-0.6.0 written to work/ex/pr-58899/sources/master#c0086b9e8972fef9fd4af24bae20d45021ed06c6/reg/bui-backend/0.6.0/Cargo.toml
[INFO] started frobbing bui-backend-0.6.0
[INFO] finished frobbing bui-backend-0.6.0
[INFO] frobbed toml for bui-backend-0.6.0 written to work/ex/pr-58899/sources/try#290ac7b29f41ff9fa5232f9a1116ea71a3501063/reg/bui-backend/0.6.0/Cargo.toml
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+c0086b9e8972fef9fd4af24bae20d45021ed06c6-alt" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] [stderr] error: failed to select a version for the requirement `ring = "^0.12.0"`
[INFO] [stderr]   candidate versions found which didn't match: 0.14.6, 0.14.5, 0.14.4, ...
[INFO] [stderr]   location searched: crates.io index
[INFO] [stderr] required by package `jsonwebtoken v4.0.0`
[INFO] [stderr]     ... which is depended on by `bui-backend v0.6.0 (/mnt/big/crater/work/ex/pr-58899/sources/master#c0086b9e8972fef9fd4af24bae20d45021ed06c6/reg/bui-backend/0.6.0)`
[ERROR] this task or one of its parent failed!
[ERROR] command `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+c0086b9e8972fef9fd4af24bae20d45021ed06c6-alt" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"` failed