Use product_ean module.

.drone.yml

@@ -15,7 +15,7 @@ pipeline:
             - pip install tox
             - tox -e "${TOXENV}-${DATABASE}"
         volumes:
-            - cache:/root/.cache
+            - /var/lib/cache:/root/.cache
     notify:
         image: drillster/drone-email
         from: drone@datalife.com.es

setup.py

@@ -10,7 +10,8 @@ from configparser import ConfigParser
 
 MODULE2PREFIX = {
     'incoterm': 'datalife',
-    'stock_unit_load': 'datalife'
+    'stock_unit_load': 'datalife',
+    'product_ean': 'datalife'
 }
 
 
@@ -64,7 +65,14 @@ dependency_links = {
         '#egg=datalife_stock_unit_load-%(series)s' % {
             'branch': branch,
             'series': series,
-            }
+            },
+    'product_ean':
+        'hg+https://bitbucket.org/datalife_sco/'
+        'trytond-product_ean@%(branch)s'
+        '#egg=datalife_product_ean-%(series)s' % {
+            'branch': branch,
+            'series': series,
+            },
 }
 
 requires = []

stock.py

@@ -4,6 +4,7 @@ from trytond.model import fields, ModelSQL
 from trytond.pool import PoolMeta, Pool
 from trytond.tools.multivalue import migrate_property
 from trytond.modules.company.model import CompanyValueMixin
+from trytond.modules.product_ean.tools import get_control_digit
 from trytond import backend
 
 __all__ = ['Configuration', 'ConfigurationSequence', 'UnitLoad',
@@ -108,15 +109,8 @@ class UnitLoad(metaclass=PoolMeta):
                          if identifier.type == 'EDI_sender']
             edi_code = edi_codes[0][:6] if edi_codes else '000000'
             code = '00' + edi_code + self.code[-9:].zfill(len(self.code[-9:])-9)
-            return code + str(self._sscc_control_digit(code))
+            return code + get_control_digit(code)
         return ''
 
     def get_grai(self):
         return ''
-
-    @staticmethod
-    def _sscc_control_digit(num):
-        nums = (int(c) for c in num)
-        multipliers = [3, 1]
-        return 10 - sum((digit * multipliers[index % 2]
-            for index, digit in enumerate(nums))) % 10

tryton.cfg

@@ -8,6 +8,7 @@ depends:
     product
     incoterm
     stock_unit_load
+    product_ean
 
 xml:
     stock.xml