message: revert --color=always changes
diff: @@ -952,17 +952,8 @@ fn phase_runner(binary: &Path, binary_args: env::Args, phase: RunnerPhase) {
  assert!(suffix.starts_with('='));
  // Drop this argument.
  } else if let Some(suffix) = arg.strip_prefix(json_flag) {
  - let suffix = suffix.strip_prefix('=').unwrap();
  - // This is how we pass through --color=always. We detect that Cargo is detecting rustc
  - // to emit the diagnostic structure that Cargo would consume from rustc to emit colored
  - // diagnostics, and ask rustc to emit them.
  - // See https://github.com/rust-lang/miri/issues/2037
  - // First skip over the leading `=`, then check for diagnostic-rendered-ansi in the
  - // comma-separated list
  - if suffix.split(',').any(|a| a == "diagnostic-rendered-ansi") {
  - cmd.arg("--color=always");
  - }
  - // But aside from remembering that colored output was requested, drop this argument.
  + assert!(suffix.starts_with('='));
  + // Drop this argument.
  } else {
  cmd.arg(arg);
  }
  