Make test_distutils pass without zlib (fixes #9435)

tests/test_sdist.py

@@ -388,6 +388,7 @@ class SDistTestCase(PyPIRCCommandTestCase):
         self.assertEqual(len(manifest2), 6)
         self.assertIn('doc2.txt', manifest2[-1])
 
+    @unittest.skipUnless(zlib, "requires zlib")
     def test_manifest_marker(self):
         # check that autogenerated MANIFESTs have a marker
         dist, cmd = self.get_cmd()
@@ -404,6 +405,7 @@ class SDistTestCase(PyPIRCCommandTestCase):
         self.assertEqual(manifest[0],
                          '# file GENERATED by distutils, do NOT edit')
 
+    @unittest.skipUnless(zlib, "requires zlib")
     def test_manual_manifest(self):
         # check that a MANIFEST without a marker is left alone
         dist, cmd = self.get_cmd()