Auto merge of #1401 - RalfJung:cargo-miri-help, r=RalfJung
Auto merge of #1401 - RalfJung:cargo-miri-help, r=RalfJung

fix cargo-miri intercepting --help/--version arguments

With this, `cargo miri test -- -- --help` should behave as expected and pass `--help` to the test runner.

Thanks to @brson for the report.

rust-lang/miri,rust-lang/miri,rust-lang/miri,rust-lang/miri