Fix source directory utime in unit test (#14595)

We need to set mtime after generating our test data otherwise
we get invalid results.

tests/unit/test_copytree.py

@@ -82,7 +82,6 @@ def create_test_data(target: str, symlink_target_path) -> None:
         os.setxattr(source, xat_name, xat_data)
 
     os.chown(source, JENNY + 10, JENNY + 11)
-    os.utime(source, ns=(JENNY + 5, JENNY + 6))
     os.chmod(source, 0o777)
 
     create_test_files(source, symlink_target_path)
@@ -110,6 +109,8 @@ def create_test_data(target: str, symlink_target_path) -> None:
         create_test_files(path, os.path.join(target, dirname))
         os.utime(path, ns=(JENNY + 3, JENNY + 4))
 
+    os.utime(source, ns=(JENNY + 5, JENNY + 6))
+
 
 @pytest.fixture(scope="function")
 def directory_for_test(tmpdir):