tests: fix indentation stable

tests: fix indentation

--- a/tests/test-bundle2-format.t	Tue Jun 02 20:40:06 2020 +0900
+++ b/tests/test-bundle2-format.t	Fri Jun 05 04:10:37 2020 +0200
@@ -148,7 +148,7 @@
   >        bundler.newpart(b'output', data=genraise(), mandatory=False)
   > 
   >     if path is None:
-  >        file = pycompat.stdout
+  >         file = pycompat.stdout
   >     else:
   >         file = open(path, 'wb')
   >