Issue #15364: Fix test_srcdir for the installed case.
diff --git a/Lib/test/test_sysconfig.py b/Lib/test/test_sysconfig.py
index 059e4c1..9219360 100644
--- a/Lib/test/test_sysconfig.py
+++ b/Lib/test/test_sysconfig.py
@@ -354,7 +354,8 @@
             self.assertTrue(os.path.exists(Python_h), Python_h)
             self.assertTrue(sysconfig._is_python_source_dir(srcdir))
         elif os.name == 'posix':
-            self.assertEqual(sysconfig.get_makefile_filename(), srcdir)
+            self.assertEqual(os.path.dirname(sysconfig.get_makefile_filename()),
+                                srcdir)
 
     def test_srcdir_independent_of_cwd(self):
         # srcdir should be independent of the current working directory