message: Avoid calling `build_command` in `fn cached_output`
diff: @@ -231,10 +231,7 @@ impl Cache {
  } else {
  debug!("rustc info cache miss");
  debug!("running {}", cmd);
  - let output = cmd
  - .build_command()
  - .output()
  - .with_context(|| format!("could not execute process {} (never executed)", cmd))?;
  + let output = cmd.output()?;
  let stdout = String::from_utf8(output.stdout)
  .map_err(|e| anyhow::anyhow!("{}: {:?}", e, e.as_bytes()))
  .with_context(|| format!("`{}` didn't return utf8 output", cmd))?;
  