cmd/internal/script: fix copying directory when symlink fails

The change fixes `linkOrCopy` to work on systems wihtout symlinks,
when copying directories.  This was originally noticed on Windows
systems when the user did not have admin privs.

Fixes #73692
Change-Id: I8ca66d65e99433ad38e70314abfabafd43794b79
Reviewed-on: https://go-review.googlesource.com/c/go/+/672275
Reviewed-by: Michael Matloob <matloob@golang.org>
Reviewed-by: Michael Matloob <matloob@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Author: jitsu-net

src/cmd/internal/script/scripttest/setup.go

@@ -114,6 +114,16 @@ func linkOrCopy(t *testing.T, src, dst string) {
 	if err == nil {
 		return
 	}
+	fi, err := os.Stat(src)
+	if err != nil {
+		t.Fatalf("copying %s to %s: %v", src, dst, err)
+	}
+	if fi.IsDir() {
+		if err := os.CopyFS(dst, os.DirFS(src)); err != nil {
+			t.Fatalf("copying %s to %s: %v", src, dst, err)
+		}
+		return
+	}
 	srcf, err := os.Open(src)
 	if err != nil {
 		t.Fatalf("copying %s to %s: %v", src, dst, err)