Issue #10253: FileIO leaks a file descriptor when trying to open a file
for append that isn't seekable.  Patch by Brian Brazil.
diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
index 4b48d41..350ba5d 100644
--- a/Lib/test/test_fileio.py
+++ b/Lib/test/test_fileio.py
@@ -339,6 +339,7 @@
         f.truncate(15)
         self.assertEqual(f.tell(), 5)
         self.assertEqual(f.seek(0, os.SEEK_END), 15)
+        f.close()
 
     def testTruncateOnWindows(self):
         def bug801631():