[INFO] updating cached repository timmc/cavern
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/timmc/cavern
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/timmc/cavern" "work/ex/pr-57617/sources/master#e2f221c75932de7a29845c8d6f1f73536ad00c41/gh/timmc/cavern"`
[INFO] [stderr] Cloning into 'work/ex/pr-57617/sources/master#e2f221c75932de7a29845c8d6f1f73536ad00c41/gh/timmc/cavern'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/timmc/cavern" "work/ex/pr-57617/sources/try#0bfb90d213a93e466b33d078a5b535a2a6f9c5ff/gh/timmc/cavern"`
[INFO] [stderr] Cloning into 'work/ex/pr-57617/sources/try#0bfb90d213a93e466b33d078a5b535a2a6f9c5ff/gh/timmc/cavern'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 66d7d176b1e4ed72d443f0d2a0e7e600edd1b038
[INFO] sha for GitHub repo timmc/cavern: 66d7d176b1e4ed72d443f0d2a0e7e600edd1b038
[INFO] validating manifest of timmc/cavern on toolchain master#e2f221c75932de7a29845c8d6f1f73536ad00c41
[ERROR] this task or one of its parent failed!
[ERROR] overridden task result to build-fail:broken
[ERROR] caused by: missing Cargo.toml for timmc/cavern
[ERROR]