diff --git a/swh/lister/core/indexing_lister.py b/swh/lister/core/indexing_lister.py
--- a/swh/lister/core/indexing_lister.py
+++ b/swh/lister/core/indexing_lister.py
@@ -148,8 +148,6 @@
         t = self.db_session.query(func.min(self.MODEL.indexable)).first()
         if t:
             return t[0]
-        else:
-            return None
 
     def db_last_index(self):
         """Look in the db for the largest indexable value
@@ -160,8 +158,6 @@
         t = self.db_session.query(func.max(self.MODEL.indexable)).first()
         if t:
             return t[0]
-        else:
-            return None
 
     def disable_deleted_repo_tasks(self, start, end, keep_these):
         """Disable tasks for repos that no longer exist between start and end.
diff --git a/swh/lister/core/tests/test_lister.py b/swh/lister/core/tests/test_lister.py
--- a/swh/lister/core/tests/test_lister.py
+++ b/swh/lister/core/tests/test_lister.py
@@ -67,8 +67,6 @@
         m = self.test_re.search(request.path_url)
         if m and (len(m.groups()) > 0):
             return m.group(1)
-        else:
-            return None
 
     def mock_response(self, request, context):
         self.fl.reset_backoff()
@@ -76,16 +74,17 @@
         context.status_code = 200
         custom_headers = self.response_headers(request)
         context.headers.update(custom_headers)
-        if self.request_index(request) == str(self.first_index):
-            with open('swh/lister/%s/tests/%s' % (self.lister_subdir,
-                                                  self.good_api_response_file),
-                      'r', encoding='utf-8') as r:
-                return r.read()
+        req_index = self.request_index(request)
+
+        if req_index == str(self.first_index):
+            response_file = self.good_api_response_file
         else:
-            with open('swh/lister/%s/tests/%s' % (self.lister_subdir,
-                                                  self.bad_api_response_file),
-                      'r', encoding='utf-8') as r:
-                return r.read()
+            response_file = self.bad_api_response_file
+
+        with open('swh/lister/%s/tests/%s' % (self.lister_subdir,
+                                              response_file),
+                  'r', encoding='utf-8') as r:
+            return r.read()
 
     def mock_limit_n_response(self, n, request, context):
         self.fl.reset_backoff()
diff --git a/swh/lister/github/lister.py b/swh/lister/github/lister.py
--- a/swh/lister/github/lister.py
+++ b/swh/lister/github/lister.py
@@ -34,15 +34,12 @@
             reset_at = int(response.headers['X-RateLimit-Reset'])
             delay = min(reset_at - time.time(), 3600)
             return True, delay
-        else:
-            return False, 0
+        return False, 0
 
     def get_next_target_from_response(self, response):
         if 'next' in response.links:
             next_url = response.links['next']['url']
             return int(self.API_URL_INDEX_RE.match(next_url).group(1))
-        else:
-            return None
 
     def transport_response_simplified(self, response):
         repos = response.json()
diff --git a/swh/lister/phabricator/lister.py b/swh/lister/phabricator/lister.py
--- a/swh/lister/phabricator/lister.py
+++ b/swh/lister/phabricator/lister.py
@@ -91,8 +91,7 @@
         body = response.json()['result']['cursor']
         if body['after'] != 'null':
             return body['after']
-        else:
-            return None
+        return None
 
     def transport_response_simplified(self, response):
         repos = response.json()