Add news, fix dir copy

news/81.bugfix

+Fix wheel builds when `package_dir` is mapped.

news/81.feature

+Add test cases for `pdm build`.

tests/conftest.py

@@ -4,6 +4,7 @@ import json
 import os
 import shutil
 import sys
+from distutils.dir_util import copy_tree
 from io import BytesIO
 from pathlib import Path
 from typing import Callable, Iterable, List, Optional, Tuple
@@ -265,7 +266,7 @@ def fixture_project(project_no_init):
 
     def func(project_name):
         source = FIXTURES / "projects" / project_name
-        shutil.copytree(source, project_no_init.root, dirs_exist_ok=True)
+        copy_tree(source.as_posix(), project_no_init.root.as_posix())
         return project_no_init
 
     return func