--- a/mercurial/localrepo.py	Sat Apr 14 02:06:03 2018 +0530
+++ b/mercurial/localrepo.py	Fri Apr 13 18:17:45 2018 -0400
@@ -184,7 +184,7 @@
         try:
             result = fn(**args)
         except Exception:
-            f.set_exception_info(*sys.exc_info()[1:])
+            pycompat.future_set_exception_info(f, sys.exc_info()[1:])
         else:
             f.set_result(result)