diff --git a/mercurial/utils/procutil.py b/mercurial/utils/procutil.py
--- a/mercurial/utils/procutil.py
+++ b/mercurial/utils/procutil.py
@@ -656,7 +656,7 @@
                 stdin.seek(0)
 
             p = subprocess.Popen(
-                tonativestr(script),
+                pycompat.rapply(tonativestr, script),
                 shell=shell,
                 env=tonativeenv(env),
                 close_fds=True,