diff --git a/mercurial/dispatch.py b/mercurial/dispatch.py
--- a/mercurial/dispatch.py
+++ b/mercurial/dispatch.py
@@ -253,7 +253,7 @@
         status = -1
 
     ret = _flushstdio(req.ui, err)
-    if ret:
+    if ret and not status:
         status = ret
     return status