bpo-38453: Resolve test directories before chdir to them (GH-16723)

Lib/test/support/__init__.py

@@ -1068,7 +1068,7 @@ def change_cwd(path, quiet=False):
     """
     saved_dir = os.getcwd()
     try:
-        os.chdir(path)
+        os.chdir(os.path.realpath(path))
     except OSError as exc:
         if not quiet:
             raise