Backport support.change_cwd() and use it in tests.
diff --git a/Lib/test/test_pep277.py b/Lib/test/test_pep277.py
index 92b82d0..cbc36cf 100644
--- a/Lib/test/test_pep277.py
+++ b/Lib/test/test_pep277.py
@@ -164,17 +164,11 @@
         dirname = os.path.join(test_support.TESTFN,
                                u'Gr\xfc\xdf-\u66e8\u66e9\u66eb')
         filename = u'\xdf-\u66e8\u66e9\u66eb'
-        oldwd = os.getcwd()
-        os.mkdir(dirname)
-        os.chdir(dirname)
-        try:
+        with test_support.temp_cwd(dirname):
             with open(filename, 'w') as f:
                 f.write((filename + '\n').encode("utf-8"))
             os.access(filename,os.R_OK)
             os.remove(filename)
-        finally:
-            os.chdir(oldwd)
-            os.rmdir(dirname)
 
 
 class UnicodeNFCFileTests(UnicodeFileTests):