Fix python-braces format

Python str.format() is marked as `#, python-brace-format` in *.po
(portable object) files.

msgcheck/utils.py

@@ -39,6 +39,8 @@ STR_FORMATTERS.update({
         (r'[\%]{2}', '%'),
         (r'\%([.\d]+)?[bcdeEfFgGnosxX]', r''),
         (r'\%(\([^)]*\))([.\d]+)?[bcdeEfFgGnosxX]', r''),
+    ),
+    'python-brace':(
         (r'\{([^\:\}]*)?(:[^\}]*)?\}', r''),
     ),
 })

tests/test_msgcheck.py

@@ -129,6 +129,9 @@ class TestMsgCheck(unittest.TestCase):  # pylint: disable=too-many-public-method
         self.assertEqual(replace_formatters('%.02f', 'python'), '')
         self.assertEqual(replace_formatters('%(sth)s', 'python'), '')
         self.assertEqual(replace_formatters('%(sth)02f', 'python'), '')
+
+    def test_replace_formatters_python_braces(self):
+        """Test removal of formatters in a python braces string."""
         # str.format()
         conditions = (
             ('First, thou shalt count to {0}',
@@ -152,7 +155,7 @@ class TestMsgCheck(unittest.TestCase):  # pylint: disable=too-many-public-method
         )
         for condition in conditions:
             self.assertEqual(
-                replace_formatters(condition[0], 'python'),
+                replace_formatters(condition[0], 'python-brace'),
                 condition[1],
                 condition[2],
             )