--- a/mercurial/wireprotoserver.py	Tue Sep 25 08:53:20 2018 -0700
+++ b/mercurial/wireprotoserver.py	Wed Sep 26 08:46:56 2018 -0700
@@ -783,6 +783,8 @@
         self._ui = ui
         self._repo = repo
         self._fin, self._fout = procutil.protectstdio(ui.fin, ui.fout)
+        # TODO: manage the redirection flag internally by ui
+        ui._finoutredirected = (self._fin, self._fout) != (ui.fin, ui.fout)
 
         # Log write I/O to stdout and stderr if configured.
         if logfh: