hm, nope, actually:

```
james@Jamess-MBP ➜  buildrstest git:(main) ✗ pwd
/tmp/buildrstest
james@Jamess-MBP ➜  buildrstest git:(main) ✗ cat build.rs 
fn main() {
    let res = std::env::current_dir();
    panic!("{:?}", res);
}
james@Jamess-MBP ➜  buildrstest git:(main) ✗ cargo run
   Compiling buildrstest v0.1.0 (/private/tmp/buildrstest)
error: failed to run custom build command for `buildrstest v0.1.0 (/private/tmp/buildrstest)`

Caused by:
  process didn't exit successfully: `/private/tmp/buildrstest/target/debug/build/buildrstest-25b0bb54864c6afd/build-script-build` (exit status: 101)
  --- stderr
  thread 'main' panicked at 'Ok("/private/tmp/buildrstest")', build.rs:3:5
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
```