[damned-lies] Guard against None value in stats sum

[Claude Paroz <claudep src gnome org>]

commit 8ffd354271b97be0265c2a7e6bf02091a7b53d29
Author: Claude Paroz <claude 2xlibre net>
Date:   Thu Nov 8 08:44:53 2018 +0100

    Guard against None value in stats sum

 stats/models.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/stats/models.py b/stats/models.py
index ae90b4cc..f1b8f00e 100644
--- a/stats/models.py
+++ b/stats/models.py
@@ -1011,8 +1011,11 @@ class Release(models.Model):
                 ).exclude(domain__in=self.excluded_domains
                 ).filter(language=lang, branch__releases=self, domain__dtype='ui'
                 ).values('branch_id', 'domain_id', 'language__locale', 'part_po__translated', 
'part_po__fuzzy', 'part_po__untranslated')
-            all_stats_d = dict([("%d-%d-%s" % (st['branch_id'], st['domain_id'], st['language__locale']),
-                                st['part_po__translated'] + st['part_po__fuzzy'] + 
st['part_po__untranslated']) for st in all_stats])
+            all_stats_d = {
+                "%d-%d-%s" % (st['branch_id'], st['domain_id'], st['language__locale']): sum(filter(
+                    None, [st['part_po__translated'], st['part_po__fuzzy'], st['part_po__untranslated']]
+                )) for st in all_stats
+            }
         total = 0
         for stat in all_pots:
             key = "%d-%d-%s" % (stat.branch_id, stat.domain_id, lang.locale)