Merge pull request #5019 from Netflix/cn-check

replace like with is none check if cn is none

lemur/certificates/service.py

@@ -322,13 +322,17 @@ def get_certificates_with_same_cn_with_rotate_on(cn, date_created):
     date_created_max = date_created.ceil('day')
 
     query = database.session_query(Certificate)\
-        .filter(Certificate.cn.like(cn))\
         .filter(Certificate.rotation == true())\
         .filter(Certificate.not_after >= now)\
         .filter(Certificate.date_created >= date_created_min)\
         .filter(Certificate.date_created <= date_created_max)\
         .filter(not_(Certificate.replaced.any()))
 
+    if cn is not None:
+        query = query.filter(Certificate.cn.like(cn))
+    else:
+        query = query.filter(Certificate.cn.is_(None))
+
     return query.all()