GR-9152: revert unittest difflib patch

Author: cosminbasca

graalpython/lib-python/3/unittest/case.py

@@ -1090,16 +1090,14 @@ def assertSequenceEqual(self, seq1, seq2, msg=None, seq_type=None):
                 except (TypeError, IndexError, NotImplementedError):
                     differing += ('Unable to index element %d '
                                   'of second %s\n' % (len1, seq_type_name))
-        # standardMsg = differing
-        # diffMsg = '\n' + '\n'.join(
-        #     difflib.ndiff(pprint.pformat(seq1).splitlines(),
-        #                   pprint.pformat(seq2).splitlines()))
-        #
-        # standardMsg = self._truncateMessage(standardMsg, diffMsg)
-        # msg = self._formatMessage(msg, standardMsg)
-        # self.fail(msg)
-        # TODO: Truffle reneable me once pformat / difflib work (GR-9152) (GR-9153)
-        self.fail(differing)
+        standardMsg = differing
+        diffMsg = '\n' + '\n'.join(
+            difflib.ndiff(pprint.pformat(seq1).splitlines(),
+                          pprint.pformat(seq2).splitlines()))
+
+        standardMsg = self._truncateMessage(standardMsg, diffMsg)
+        msg = self._formatMessage(msg, standardMsg)
+        self.fail(msg)
 
     def _truncateMessage(self, message, diff):
         max_diff = self.maxDiff