Allow longer tuples in error messages. Fixes #287.

Author: Guido van Rossum

mypy/messages.py

@@ -250,7 +250,7 @@ def format_simple(self, typ: Type, verbosity: int = 0) -> str:
             for t in typ.items:
                 items.append(strip_quotes(self.format(t)))
             s = '"Tuple[{}]"'.format(', '.join(items))
-            if len(s) < 40:
+            if len(s) < 400:
                 return s
             else:
                 return 'tuple(length {})'.format(len(items))