diff --git a/swh/storage/tests/test_storage.py b/swh/storage/tests/test_storage.py
--- a/swh/storage/tests/test_storage.py
+++ b/swh/storage/tests/test_storage.py
@@ -13,7 +13,6 @@
 import psycopg2
 from nose.plugins.attrib import attr
 
-from swh.core.tests.db_testing import DbTestFixture
 from swh.model import from_disk, identifiers
 from swh.model.hashutil import hash_to_bytes
 from swh.storage.tests.storage_testing import StorageTestFixture
diff --git a/utils/dump_revisions.py b/utils/dump_revisions.py
--- a/utils/dump_revisions.py
+++ b/utils/dump_revisions.py
@@ -8,6 +8,7 @@
 from swh.storage import converters, db
 from swh.model import identifiers
 
+
 QUERY = '''
 select
   r.id,
@@ -44,6 +45,7 @@
     if id != computed_id:
         dump_revision(revision)
 
+
 if __name__ == '__main__':
     swh_db = db.Db.connect('service=swh',
                            cursor_factory=psycopg2.extras.RealDictCursor)
diff --git a/utils/fix_revisions_from_dump.py b/utils/fix_revisions_from_dump.py
--- a/utils/fix_revisions_from_dump.py
+++ b/utils/fix_revisions_from_dump.py
@@ -16,6 +16,7 @@
 def author_date_to_negutc(rev):
     rev['date']['negative_utc'] = True
 
+
 DATE_NEGUTC_FIX = ('set author negutc', [
     (None, None),
     (author_date_to_negutc, 'date_neg_utcoffset = true'),
@@ -29,6 +30,7 @@
 def committer_date_to_negutc(rev):
     rev['committer_date']['negative_utc'] = True
 
+
 COMMITTER_DATE_NEGUTC_FIX = ('set committer negutc', [
     (None, None),
     (committer_date_to_negutc, 'committer_date_neg_utcoffset = true'),
@@ -38,6 +40,7 @@
 def message_to_empty(rev):
     rev['message'] = b''
 
+
 MESSAGE_EMPTY_FIX = ('empty instead of null message', [
     (None, None),
     (message_to_empty, "message = ''"),
@@ -47,6 +50,7 @@
 def message_to_null(rev):
     rev['message'] = None
 
+
 MESSAGE_NULL_FIX = ('null instead of empty message', [
     (None, None),
     (message_to_null, "message = NULL"),
@@ -88,6 +92,7 @@
 def author_name_doublespace(rev):
     rev['author']['name'] = b''.join([rev['author']['name'], b' '])
 
+
 AUTHOR_NAME_ADD_SPC_FIX = ('author double space', [
     (None, None),
     (author_name_doublespace, 'trailing space author name')
@@ -97,6 +102,7 @@
 def committer_name_doublespace(rev):
     rev['committer']['name'] = b''.join([rev['committer']['name'], b' '])
 
+
 COMMITTER_NAME_ADD_SPC_FIX = ('committer double space', [
     (None, None),
     (committer_name_doublespace, 'trailing space committer name')
@@ -106,6 +112,7 @@
 def author_name_null(rev):
     rev['author']['name'] = None
 
+
 AUTHOR_NAME_NULL_FIX = ('author name null', [
     (None, None),
     (author_name_null, 'None author name')
@@ -115,6 +122,7 @@
 def author_email_null(rev):
     rev['author']['email'] = None
 
+
 AUTHOR_EMAIL_NULL_FIX = ('author email null', [
     (None, None),
     (author_email_null, 'None author email')
@@ -124,6 +132,7 @@
 def committer_name_null(rev):
     rev['committer']['name'] = None
 
+
 COMMITTER_NAME_NULL_FIX = ('committer name null', [
     (None, None),
     (committer_name_null, 'None committer name')
@@ -133,6 +142,7 @@
 def committer_email_null(rev):
     rev['committer']['email'] = None
 
+
 COMMITTER_EMAIL_NULL_FIX = ('committer email null', [
     (None, None),
     (committer_email_null, 'None committer email')
@@ -143,6 +153,7 @@
     rev['author'] = b''.join([
         identifiers.normalize_author(rev['author']), b' '])
 
+
 AUTHOR_ADD_SPC_FIX = ('add trailing space to author specification', [
     (None, None),
     (author_add_spc, 'add trailing space to author spec')
@@ -153,6 +164,7 @@
     rev['committer'] = b''.join([
         identifiers.normalize_author(rev['committer']), b' '])
 
+
 COMMITTER_ADD_SPC_FIX = ('add trailing space to committer specification', [
     (None, None),
     (committer_add_spc, 'add trailing space to committer spec')
@@ -224,6 +236,7 @@
     else:
         return id, []
 
+
 if __name__ == '__main__':
 
     for hash in sys.stdin.readlines():