'index out of bounds' panic on beta on Travis macOS

[oconnor663]

As of yesterday's release, I've started seeing a Cargo panic in my CI, only on macOS hosts with the beta compiler (no repro on nightly):

thread 'main' panicked at 'index out of bounds: the len is 2 but the index is 2', src/tools/cargo/src/cargo/util/cpu.rs:152:29

Here are builds from two different projects demonstrating the panic:

https://travis-ci.org/oconnor663/duct.rs/jobs/590451953
https://travis-ci.org/oconnor663/os_pipe.rs/builds/590452207

[pnkfelix]

I saw @RalfJung mention something similar over here: rust-lang/rust#64798 (comment)

[alexcrichton]

Thanks for the report! This was fixed in #7429 and landed in the rust repo a few hours ago for the beta branch at rust-lang/rust#64814, and the fix should propagate to the beta channel tonight.