Fix for invoices with date <= 1900

Because the helper script for invoice, (order, packing lists, etc) printout is using `DateTime.strftime` it does not support dates before 1900.
This is a [documented behavior](https://docs.python.org/2/library/datetime.html#strftime-and-strptime-behavior) in python that dates before 1900 cannot be used.

In these cases it's not supposed to happen, but if by mistake user enter a date before 1900, printing the invoice would fail, which is not good.

These patterns were very simple and did not need strftime.

/reviewed-on !694

bt5/erp5_base/SkinTemplateItem/portal_skins/erp5_base/Delivery_getODTDataDict.py

@@ -63,13 +63,15 @@ def getSocialCapital(reg_cap):
 
 preferred_date_order = context.getPortalObject().portal_preferences\
                                           .getPreferredDateOrder() or 'ymd'
-separator = '/'
 def getOrderedDate(date):
   if date is None:
     return ''
-  pattern = separator.join(['%%%s' % s for s in list(preferred_date_order)])
-  pattern = pattern.replace('y', 'Y')
-  return date.strftime(pattern)
+  date_parts = {
+    'y': '%04d' % date.year(),
+    'm': '%02d' % date.month(),
+    'd': '%02d' % date.day(),
+  }
+  return '/'.join([date_parts[part] for part in preferred_date_order])
 
 def getPaymentConditionText(order):
   if 'custom' == order.getPaymentConditionTradeDate():

bt5/erp5_payroll/SkinTemplateItem/portal_skins/erp5_payroll/PaySheetTransaction_getODTDataDict.py

@@ -73,13 +73,15 @@ def getCareerId(career_title):
 
 preferred_date_order = context.getPortalObject().portal_preferences\
                                           .getPreferredDateOrder() or 'ymd'
-separator = '/'
 def getOrderedDate(date):
   if date is None:
     return ''
-  pattern = separator.join(['%%%s' % s for s in list(preferred_date_order)])
-  pattern = pattern.replace('y', 'Y')
-  return date.strftime(pattern)
+  date_parts = {
+    'y': '%04d' % date.year(),
+    'm': '%02d' % date.month(),
+    'd': '%02d' % date.day(),
+  }
+  return '/'.join([date_parts[part] for part in preferred_date_order])
 
 def getPaymentConditionText(order):
   if order.getPaymentConditionPaymentEndOfMonth():

bt5/erp5_payroll_l10n_fr/SkinTemplateItem/portal_skins/erp5_payroll_l10n_fr/PaySheetTransaction_getOtherInformationsDataDict.py

@@ -100,13 +100,15 @@ year_to_date_total_employer_tax = paysheet.PaySheetTransaction_getYearToDateMove
 
 preferred_date_order = portal.portal_preferences\
                        .getPreferredDateOrder() or 'ymd'
-separator = '/'
 def getOrderedDate(date):
   if date is None:
     return ''
-  pattern = separator.join(['%%%s' % s for s in list(preferred_date_order)])
-  pattern = pattern.replace('y', 'Y')
-  return date.strftime(pattern)
+  date_parts = {
+    'y': '%04d' % date.year(),
+    'm': '%02d' % date.month(),
+    'd': '%02d' % date.day(),
+  }
+  return '/'.join([date_parts[part] for part in preferred_date_order])
 
 def getPaymentConditionText(paysheet):
   date = ''

product/ERP5/tests/testInvoice.py

@@ -1762,6 +1762,53 @@ class TestInvoice(TestInvoiceMixin):
     if err_list:
       self.fail(''.join(err_list))
 
+  def test_Invoice_viewAsODT_date_before_1900(self):
+    # Regression test for invoices with a date before 1900, which
+    # python-2.7's strftime does not support.
+    resource = self.portal.getDefaultModule(
+        self.resource_portal_type
+    ).newContent(
+        portal_type=self.resource_portal_type,
+        title='Resource',)
+    file_data = FileUpload(__file__)
+    client = self.portal.organisation_module.newContent(
+        portal_type='Organisation',
+        title='Client')
+    vendor = self.portal.organisation_module.newContent(
+        portal_type='Organisation',
+        title='Vendor')
+
+    invoice = self.portal.getDefaultModule(
+        self.invoice_portal_type
+    ).newContent(
+        portal_type=self.invoice_portal_type,
+        start_date=DateTime(102, 12, 31),
+        stop_date=DateTime(103, 12, 31),
+        title='Invoice',
+        specialise=self.business_process,
+        source_value=vendor,
+        source_section_value=vendor,
+        destination_value=client,
+        destination_section_value=client)
+    invoice.newContent(
+        portal_type=self.invoice_line_portal_type,
+        resource_value=resource,
+        quantity=10,
+        price=3)
+    invoice.confirm()
+    self.tic()
+
+    data_dict = invoice.Invoice_getODTDataDict()
+    self.assertEqual('0102/12/31', data_dict['start_date'])
+    self.assertEqual('0103/12/31', data_dict['stop_date'])
+    # rendering is valid odf
+    odt = invoice.Invoice_viewAsODT()
+    from Products.ERP5OOo.tests.utils import Validator
+    odf_validator = Validator()
+    err_list = odf_validator.validate(odt)
+    if err_list:
+      self.fail(''.join(err_list))
+
   def test_invoice_building_with_cells(self):
     # if the order has cells, the invoice built from that order must have
     # cells too