Decimal escape is not right in python 2.x

[limodou]

Today I found the similary issue #217 but this time is Decimal datatype, because after #221 all unicode will be converted to string, but Decimal will be converted to unicode, for example:

>>> from pymysql.converters import escape_item
>>> from decimal import Decimal
>>> escape_item(Decimal('0.4'), 'utf8')
u'0.4'

So this will cause encode error with other non-ascii strings.

And I tried to fix it, the code is:

diff --git a/pymysql/converters.py b/pymysql/converters.py
index 4f22762..daa00f7 100644
--- a/pymysql/converters.py
+++ b/pymysql/converters.py
@@ -58,6 +58,9 @@ def escape_int(value):
 def escape_float(value):
     return ('%.15g' % value)

+def escape_decimal(value):
+    return str(value)
+
 def escape_string(value):
     return ("%s" % (ESCAPE_REGEX.sub(
             lambda match: ESCAPE_MAP.get(match.group(0)), value),))
@@ -292,7 +295,7 @@ encoders = {
         datetime.timedelta : escape_timedelta,
         datetime.time : escape_time,
         time.struct_time : escape_struct_time,
-        Decimal: text_type,
+        Decimal: escape_decimal,
         }