pep517 backend - Copy symlinks when copying source (#80690)

changelogs/fragments/pep517-backend-traceback-fix.yml

@@ -0,0 +1,3 @@
+bugfixes:
+  - pep517 build backend - Copy symlinks when copying the source tree.
+    This avoids tracebacks in various scenarios, such as when a venv is present in the source tree.

packaging/pep517_backend/_backend.py

@@ -118,7 +118,7 @@ def build_sdist(  # noqa: WPS210, WPS430
     original_src_dir = Path.cwd().resolve()
     with _run_in_temporary_directory() as tmp_dir:
         tmp_src_dir = Path(tmp_dir) / 'src'
-        copytree(original_src_dir, tmp_src_dir)
+        copytree(original_src_dir, tmp_src_dir, symlinks=True)
         os.chdir(tmp_src_dir)
 
         if build_manpages_requested: