accounting: consider mirror node as an extra grouping parameter

Even if this is incorrect to allow grouping lines where mirror account does not match, we want to make it possible for sites where mirror account is not used consistently to group without having to migrate the data. So we make this possible by leaving them a chance to customize AccountingTransactionLine_getGroupingExtraParameterList to ignore mirror account.

bt5/erp5_accounting/SkinTemplateItem/portal_skins/erp5_accounting/AccountingTransactionLine_getGroupingExtraParameterList.py

@@ -5,3 +5,19 @@ For instance, we can refuse to group together lines for different order by retur
 
 The returned value must be hashable.
 """
+
+# By default we take into account mirror section.
+# The rationale is that when using internal accounting transaction between
+# two entities of the group, the grouping has to be valid for both sides
+# (source_section & destination_section).
+
+# This behavior was introduced in nexedi/erp5@f3bebea3 for compatibility,
+# some old sites where accounting lines have been grouped together regardless of
+# the mirror node can decide to ignore the mirror account.
+# Maybe to ignore mirror account for transactions created before the date they
+# deployed this new versions.
+# This can be achieved easily by customizing this script.
+
+if source:
+  return context.getSource(portal_type='Account')
+return context.getDestination(portal_type='Account')

bt5/erp5_accounting/SkinTemplateItem/portal_skins/erp5_accounting/AccountingTransaction_guessGroupedLines.py

@@ -7,7 +7,7 @@ of related accounting transactions using causality.
 
 from Products.ERP5Type.Utils import int2letter
 
-# this dict associates (node, section, mirror_section, mirror_node, extra_grouping_parameter) to a list of
+# this dict associates (node, section, mirror_section, extra_grouping_parameter) to a list of
 # accounting lines info (total_price, date and path)
 lines_per_node = {}
 
@@ -43,11 +43,11 @@ for line in accounting_transaction_line_value_list:
       source_section = \
         source_section.Organisation_getMappingRelatedOrganisation()
       section_relative_url = source_section.getRelativeUrl()
+
     lines_per_node.setdefault(
                   (line.getSource(portal_type='Account'),
                    section_relative_url,
                    line.getDestinationSection(),
-                   line.getDestination(portal_type='Account'),
                    line.AccountingTransactionLine_getGroupingExtraParameterList(source=True),
                    ), []).append(
       dict(total_price=line.getSourceInventoriatedTotalAssetPrice() or 0,
@@ -65,7 +65,6 @@ for line in accounting_transaction_line_value_list:
               (line.getDestination(portal_type='Account'),
                section_relative_url,
                line.getSourceSection(),
-               line.getSource(portal_type='Account'),
                line.AccountingTransactionLine_getGroupingExtraParameterList(source=False),
                ), []).append(
     dict(total_price=line.getDestinationInventoriatedTotalAssetPrice() or 0,
@@ -73,7 +72,7 @@ for line in accounting_transaction_line_value_list:
          path=line.getRelativeUrl()))
 
 changed_line_list = []
-for (node, section, mirror_section, mirror_node, extra_parameter), line_info_list in lines_per_node.items():
+for (node, section, mirror_section, _), line_info_list in lines_per_node.items():
   if node is None:
     continue
   total_price = sum([l['total_price'] for l in line_info_list])