Fix error message

Author: asvetlov

aiohttp/multidict.py

@@ -15,8 +15,8 @@ class MultiDict(abc.Mapping):
 
     def __init__(self, *args, **kwargs):
         if len(args) > 1:
-            raise TypeError("MultiDict takes at most 2 positional "
-                            "arguments ({} given)".format(len(args) + 1))
+            raise TypeError("MultiDict takes at most 1 positional "
+                            "argument ({} given)".format(len(args)))
         self._items = []
         if args:
             if hasattr(args[0], 'items'):

tests/test_multidict.py

@@ -21,7 +21,7 @@ def test_instantiate__empty(self):
         self.assertEqual(list(d.items(getall=True)), [])
 
         self.assertNotEqual(self.make_dict(), list())
-        with self.assertRaisesRegex(TypeError, "\(3 given\)"):
+        with self.assertRaisesRegex(TypeError, "\(2 given\)"):
             self.make_dict(('key1', 'value1'), ('key2', 'value2'))
 
     def test_instantiate__from_arg0(self):