set, and reparse points that are not symlinks, Unix sockets, or dedup files now
always have [`os.ModeIrregular`](/pkg/os#ModeIrregular) set. As a result of these changes,
[`filepath.EvalSymlinks`](/pkg/path/filepath#EvalSymlinks) no longer evaluates
mount points, which was a source of many inconsistencies and bugs.
At previous versions (`winsymlink=0`), mount points are treated as symlinks,

func subdir() (pkgpath string, underGoRoot bool, err error) {
	cwd, err := os.Getwd()
	if err != nil {
		return "", false, err
	}
	cwd, err = filepath.EvalSymlinks(cwd)
	if err != nil {
		log.Fatal(err)
	}
	goroot, err := filepath.EvalSymlinks(runtime.GOROOT())
	if err != nil {
		return "", false, err
	}
	if strings.HasPrefix(cwd, goroot) {
		subdir, err := filepath.Rel(goroot, cwd)
		if err != nil {