Add missing order override for sequence field

issue4795
review15451002

product.py

@@ -1,5 +1,7 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
+from sql import Null
+
 from trytond.model import ModelView, ModelSQL, fields
 from trytond.pyson import Eval, Get, If, Bool
 from trytond.pool import PoolMeta
@@ -83,3 +85,8 @@ class ProductBom(ModelSQL, ModelView):
     @classmethod
     def search_rec_name(cls, name, clause):
         return [('bom.rec_name',) + tuple(clause[1:])]
+
+    @staticmethod
+    def order_sequence(tables):
+        table, _ = tables[None]
+        return [table.sequence == Null, table.sequence]

setup.py

@@ -41,7 +41,7 @@ if minor_version % 2:
         'hg+http://hg.tryton.org/modules/%s#egg=%s-%s' % (
             name[8:], name, version))
 
-requires = []
+requires = ['python-sql >= 0.4']
 for dep in info.get('depends', []):
     if not re.match(r'(ir|res|webdav)(\W|$)', dep):
         requires.append(get_require_version('trytond_%s' % dep))