fix pypy

Author: methane

tornado_mysql/cursors.py

@@ -302,7 +302,10 @@ def _do_get_result(self):
     def _show_warnings(self, conn):
         ws = yield conn.show_warnings()
         for w in ws:
-            warnings.warn(w[-1], err.Warning, 4)
+            msg = w[-1]
+            if PY2 and isinstance(msg, unicode):
+                msg = msg.encode('utf-8', 'replace')
+            warnings.warn(msg, err.Warning, 4)
 
     def __iter__(self):
         return iter(self.fetchone, None)