fix flake

Author: Byron

git/index/base.py

@@ -1031,6 +1031,7 @@ def checkout(self, paths=None, force=False, fprogress=lambda *args: None, **kwar
         failed_files = []
         failed_reasons = []
         unknown_lines = []
+
         def handle_stderr(proc, iter_checked_out_files):
             stderr = proc.stderr.read()
             if not stderr: