Fix status output for ref changes.

Change-Id: I75b9f9b2c059fae776ab395951242cda0153c7ab
Reviewed-on: https://review.openstack.org/10996
Approved: James E. Blair <corvus@inaugust.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins
diff --git a/zuul/model.py b/zuul/model.py
index 8926e76..8c625ab 100644
--- a/zuul/model.py
+++ b/zuul/model.py
@@ -118,7 +118,7 @@
     def formatStatus(self, changeish, indent=0, html=False):
         indent_str = ' ' * indent
         ret = ''
-        if html and changeish.url is not None:
+        if html and hasattr(changeish, 'url') and changeish.url is not None:
             ret += '%sProject %s change <a href="%s">%s</a>\n' % (
                 indent_str,
                 changeish.project.name,