From f84e1dc993fa02f641d495fc2097d2a391e2db0a Mon Sep 17 00:00:00 2001
From: Albert Cervera i Areny <albert@nan-tic.com>
Date: Thu, 2 May 2013 00:47:50 +0200
Subject: [PATCH] Avoid crash when back_leveling_delay is None.

issue3195
review785002
(transplanted from fcd869cb3d0c35b2aa5907ef5ad4fe0202b8a8d8)
---
 work.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/work.py b/work.py
index d71cc4b2b9..15420151e3 100644
--- a/work.py
+++ b/work.py
@@ -484,7 +484,7 @@ class Work:
 
             if constraint_finish:
                 late_finish = self.add_hours(work.company, constraint_finish,
-                        -work.back_leveling_delay)
+                        -(work.back_leveling_delay or 0.0))
             else:
                 late_finish = None