Fix for py3x, again

Author: mlongtin0

pymysql/cursors.py

@@ -147,7 +147,7 @@ def executemany(self, query, args):
         if m:
             q_prefix = m.group(1)
             q_values = m.group(2).rstrip()
-            q_postfix = bytearray(m.group(3) or '')
+            q_postfix = m.group(3) or ''
             assert q_values[0] == '(' and q_values[-1] == ')'
             return self._do_execute_many(q_prefix, q_values, q_postfix, args,
                                          self.max_stmt_length,
@@ -161,6 +161,8 @@ def _do_execute_many(self, prefix, values, postfix, args, max_stmt_length, encod
         escape = self._escape_args
         if isinstance(prefix, text_type):
             prefix = prefix.encode(encoding)
+        if isinstance(postfix, text_type):
+            postfix = postfix.encode(encoding)
         sql = bytearray(prefix)
         args = iter(args)
         v = values % escape(next(args), conn)