[FIX] membership_extension: Don't return early + remove condition

- Don't return before consuming whole recordset.
- The 'cancelled' state is no covered upstream through 'reverse_entry_id'.

membership_extension/models/membership_line.py

@@ -43,16 +43,14 @@ def _onchange_membership_date(self):
                     self.date_to = date_to
 
     def _compute_state(self):
-        for line in self:
-            if isinstance(line.id, models.NewId) or not line.account_invoice_id:
-                line.state = line.state or "none"
-            elif (
-                line.account_invoice_id.state == "posted"
-                and line.account_invoice_id.payment_state == "reversed"
-            ):
-                line.state = "canceled"
-            else:
-                return super(MembershipLine, line)._compute_state()
+        """Allow to keep the current manual state if no linked invoice."""
+        no_invoice_lines = self.filtered(
+            lambda line: isinstance(line.id, models.NewId)
+            or not line.account_invoice_id
+        )
+        for line in no_invoice_lines:
+            line.state = line.state or "none"
+        return super(MembershipLine, self - no_invoice_lines)._compute_state()
 
     # Empty method _inverse_state
     def _inverse_state(self):