diff -r 6e2e5adc0400 Lib/tempfile.py
--- a/Lib/tempfile.py	Thu Dec 27 18:53:12 2012 -0800
+++ b/Lib/tempfile.py	Fri Dec 28 07:37:16 2012 +0200
@@ -171,10 +171,12 @@
             filename = _os.path.join(dir, name)
             try:
                 fd = _os.open(filename, _bin_openflags, 0o600)
-                fp = _io.open(fd, 'wb')
-                fp.write(b'blat')
-                fp.close()
-                _os.unlink(filename)
+                try:
+                    fp = _io.open(fd, 'wb')
+                    fp.write(b'blat')
+                    fp.close()
+                finally:
+                    _os.unlink(filename)
                 del fp, fd
                 return dir
             except FileExistsError:
diff -r 6e2e5adc0400 Lib/test/test_tempfile.py
--- a/Lib/test/test_tempfile.py	Thu Dec 27 18:53:12 2012 -0800
+++ b/Lib/test/test_tempfile.py	Fri Dec 28 07:37:16 2012 +0200
@@ -197,7 +197,35 @@
             # paths in this list.
 
 
-# We test _get_default_tempdir by testing gettempdir.
+# We test _get_default_tempdir some more by testing gettempdir.
+
+class TestGetDefaultTempdir(BaseTestCase):
+    """Test _get_default_tempdir()."""
+
+    def test_no_files_left_behind(self):
+        # use a private empty directory
+        with tempfile.TemporaryDirectory() as our_temp_directory:
+
+            # force _get_default_tempdir() to consider our empty directory
+            def our_candidate_list():
+                return [our_temp_directory]
+
+            with support.swap_attr(tempfile, "_candidate_tempdir_list", our_candidate_list):
+
+                # verify our directory is empty after _get_default_tempdir()
+                tempfile._get_default_tempdir()
+                self.assertEqual(os.listdir(our_temp_directory), [])
+
+                # make io.open() fail
+                import io
+                def raise_OSError(*args, **kwargs):
+                    raise OSError()
+
+                with support.swap_attr(io, "open", raise_OSError):
+
+                    # test again with failing io.open()
+                    self.assertRaises(OSError, tempfile._get_default_tempdir)
+                    self.assertEqual(os.listdir(our_temp_directory), [])
 
 
 class TestGetCandidateNames(BaseTestCase):