[damned-lies] Fix exception import location

[Claude Paroz <claudep src gnome org>]

commit 2ae83edc259c07923e8cedff5a76db0fe1e9933e
Author: Claude Paroz <claude 2xlibre net>
Date:   Mon Sep 17 11:41:00 2018 +0200

    Fix exception import location

 stats/models.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/stats/models.py b/stats/models.py
index 5ca2e1da..dcf98cbc 100644
--- a/stats/models.py
+++ b/stats/models.py
@@ -23,7 +23,7 @@ from django.utils import dateformat
 from django.db import models
 
 from common.fields import DictionaryField, JSONField
-from common.utils import UndetectableDocFormat, is_site_admin, run_shell_command
+from common.utils import is_site_admin, run_shell_command
 from stats import utils, signals
 from stats.doap import update_doap_infos
 from people.models import Person
@@ -788,7 +788,7 @@ class Domain(models.Model):
     def can_build_docs(self, branch):
         try:
             return self.dtype == 'doc' and self.doc_format(branch).format == 'mallard'
-        except UndetectableDocFormat:
+        except utils.UndetectableDocFormat:
             return False
 
     def get_po_path(self, locale):