From f7ff79c558c19a9562bfc2c4f407c23bebd0f4bf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Krier?= <ced@b2ck.com>
Date: Wed, 28 Nov 2018 09:58:26 +0100
Subject: [PATCH] Do not compare sequence which are None

In Python3, it is no more allowed to compare None with None or any numeric.

issue7874
review70451002
---
 invoice.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/invoice.py b/invoice.py
index d8d764192d..7866be3048 100644
--- a/invoice.py
+++ b/invoice.py
@@ -63,7 +63,11 @@ class Invoice(metaclass=PoolMeta):
         if amount < 0:
             line = self._get_deposit_recall_invoice_line(
                 amount, account, description)
-            line.sequence = max(l.sequence for l in self.lines)
+            try:
+                line.sequence = max(l.sequence for l in self.lines
+                    if l.sequence is not None)
+            except ValueError:
+                pass
             line.save()
         if to_delete:
             InvoiceLine.delete(to_delete)