Include all vendored files in the sdist.

Closes #4480

MANIFEST.in

@@ -2,7 +2,7 @@ recursive-include setuptools *.py *.exe *.xml *.tmpl
 recursive-include tests *.py
 recursive-include setuptools/tests *.html
 recursive-include docs *.py *.txt *.rst *.conf *.css *.css_t Makefile indexsidebar.html
-recursive-include setuptools/_vendor *.py *.txt
+recursive-include setuptools/_vendor *
 recursive-include pkg_resources *.py *.txt
 recursive-include pkg_resources/tests/data *
 recursive-include tools *

newsfragments/4480.bugfix.rst

@@ -0,0 +1 @@
+Include all vendored files in the sdist.

setuptools/tests/test_setuptools.py

@@ -318,7 +318,6 @@ def test_wheel_includes_cli_scripts(setuptools_wheel):
     assert any('cli-64.exe' in member for member in contents)
 
 
-@pytest.mark.xfail(reason="#4480")
 def test_wheel_includes_vendored_metadata(setuptools_wheel):
     with ZipFile(setuptools_wheel) as zipfile:
         contents = [f.replace(os.sep, '/') for f in zipfile.namelist()]