[FIX] account_reconcile_oca: Synchronize manual_partner_id with partn…

…er_id without onchange or subsequent changes with the _synchronize_to_moves() method.

We do not define partner_id with the value of manual_partner_id to prevent _synchronize_to_moves()
from making changes to the account.move.line leaving unintended values and/or data.

Related to OCA#779

TT52634

account_reconcile_oca/models/account_bank_statement_line.py

@@ -474,8 +474,6 @@ def _onchange_manual_reconcile_vals(self):
                         line["kind"] if line["kind"] != "suspense" else "other"
                     )
                     line.update(line_vals)
-                    if line["kind"] == "liquidity":
-                        self._update_move_partner()
             if self.manual_line_id and self.manual_line_id.id == line.get(
                 "original_exchange_line_id"
             ):
@@ -501,11 +499,6 @@ def _onchange_manual_reconcile_vals(self):
         )
         self.can_reconcile = self.reconcile_data_info.get("can_reconcile", False)
 
-    def _update_move_partner(self):
-        if self.partner_id == self.manual_partner_id:
-            return
-        self.partner_id = self.manual_partner_id
-
     @api.depends("reconcile_data", "is_reconciled")
     def _compute_reconcile_data_info(self):
         for record in self:
@@ -943,6 +936,34 @@ def create(self, mvals):
             )(self._prepare_reconcile_line_data(data["data"]))
         return result
 
+    def _synchronize_to_moves(self, changed_fields):
+        """Similar process to what _synchronize_to_moves() method would do but without
+        the relative to all the changed_fields, we just need to update partner_id.
+        We precisely do not do an onchange of self.partner_id = self.manual_partner_id
+        to avoid making all those unnecessary changes, but we need to apply this
+        change to the account.move and the lines without side effects.
+        A change of manual_partner_id that has been reconciled should NOT change the
+        values of the account.move lines.
+        """
+        super()._synchronize_to_moves(changed_fields=changed_fields)
+        if self._context.get("skip_account_move_synchronization"):
+            return
+
+        if not any(f_name in changed_fields for f_name in ("manual_partner_id",)):
+            return
+
+        for st_line in self.with_context(skip_account_move_synchronization=True):
+            liquidity_lines, suspense_lines, _other_lines = st_line._seek_for_lines()
+            line_vals = {"partner_id": st_line.manual_partner_id.id}
+            line_ids_commands = [(1, liquidity_lines.id, line_vals)]
+            if suspense_lines:
+                line_ids_commands.append((1, suspense_lines.id, line_vals))
+            st_line_vals = {"line_ids": line_ids_commands}
+            if st_line.move_id.partner_id != st_line.manual_partner_id:
+                st_line_vals["partner_id"] = st_line.manual_partner_id.id
+            st_line.move_id.write(st_line_vals)
+            st_line.write({"partner_id": st_line.manual_partner_id.id})
+
     def _prepare_reconcile_line_data(self, lines):
         new_lines = []
         reverse_lines = {}

account_reconcile_oca/tests/test_bank_account_reconcile.py

@@ -841,6 +841,7 @@ def test_widget_invoice_change_partner(self):
             self.assertFalse(f.partner_id)
             f.manual_reference = "account.move.line;%s" % liquidity_lines.id
             f.manual_partner_id = inv1.partner_id
+            f.save()
             self.assertEqual(f.partner_id, inv1.partner_id)
         bank_stmt_line.clean_reconcile()
         # As we have a set a partner, the cleaning should assign the invoice automatically