Fix memory error in test_ucn.

unicode-escape decoder requires memory for result corresponding to input size.
Fixes test for issue #16335.

Lib/test/test_ucn.py

@@ -222,13 +222,14 @@ class UnicodeNamesTest(unittest.TestCase):
         # very very long bogus character name
         try:
             x = b'\\N{SPACE' + b'x' * (_testcapi.UINT_MAX + 1) + b'}'
-        except MemoryError:
-            raise unittest.SkipTest("not enough memory")
-        self.assertEqual(len(x), len(b'\\N{SPACE}') + (_testcapi.UINT_MAX + 1))
+            self.assertEqual(len(x), len(b'\\N{SPACE}') +
+                                     (_testcapi.UINT_MAX + 1))
             self.assertRaisesRegex(UnicodeError,
                 'unknown Unicode character name',
                 x.decode, 'unicode-escape'
             )
+        except MemoryError:
+            raise unittest.SkipTest("not enough memory")
 
 
 def test_main():