Fix bug in diff parser outputfix-octal-escaped-path-parser-bug

The diff --patch parser was missing some edge case where Git would
encode non-ASCII chars in path names as octals, but these weren't
decoded properly.

    \360\237\222\251.txt

Decoded via utf-8, that will return:

    💩.txt

1 files changed, 7 insertions, 6 deletions

diff --git a/git/test/test_diff.py b/git/test/test_diff.py
index 1d7a4fda..8966351a 100644
--- a/git/test/test_diff.py
+++ b/git/test/test_diff.py
@@ -161,16 +161,17 @@ class TestDiff(TestBase):
         self.assertEqual(res[6].b_path, u'path/with spaces')
         self.assertEqual(res[7].b_path, u'path/with-question-mark?')
         self.assertEqual(res[8].b_path, u'path/¯\\_(ツ)_|¯')
+        self.assertEqual(res[9].b_path, u'path/💩.txt')
 
         # The "Moves"
         # NOTE: The path prefixes a/ and b/ here are legit!  We're actually
         # verifying that it's not "a/a/" that shows up, see the fixture data.
-        self.assertEqual(res[9].a_path, u'a/with spaces')       # NOTE: path a/ here legit!
-        self.assertEqual(res[9].b_path, u'b/with some spaces')  # NOTE: path b/ here legit!
-        self.assertEqual(res[10].a_path, u'a/ending in a space ')
-        self.assertEqual(res[10].b_path, u'b/ending with space ')
-        self.assertEqual(res[11].a_path, u'a/"with-quotes"')
-        self.assertEqual(res[11].b_path, u'b/"with even more quotes"')
+        self.assertEqual(res[10].a_path, u'a/with spaces')       # NOTE: path a/ here legit!
+        self.assertEqual(res[10].b_path, u'b/with some spaces')  # NOTE: path b/ here legit!
+        self.assertEqual(res[11].a_path, u'a/ending in a space ')
+        self.assertEqual(res[11].b_path, u'b/ending with space ')
+        self.assertEqual(res[12].a_path, u'a/"with-quotes"')
+        self.assertEqual(res[12].b_path, u'b/"with even more quotes"')
 
     def test_diff_patch_format(self):
         # test all of the 'old' format diffs for completness - it should at least