diff --git a/mercurial/sslutil.py b/mercurial/sslutil.py
--- a/mercurial/sslutil.py
+++ b/mercurial/sslutil.py
@@ -14,7 +14,10 @@ import ssl
 import sys
 
 from .i18n import _
-from . import error, util
+from . import (
+    error,
+    util,
+)
 
 hassni = getattr(ssl, 'HAS_SNI', False)