diff -r c3e450bfdf34 -r 7a4772e92f23 mercurial/utils/procutil.py
--- a/mercurial/utils/procutil.py	Thu Mar 06 10:15:00 2025 +0100
+++ b/mercurial/utils/procutil.py	Thu Mar 06 12:23:27 2025 +0100
@@ -743,7 +743,7 @@
             script = b' '.join(shellquote(x) for x in cmd)
         if record_wait is None:
             # double-fork to completely detach from the parent process
-            script = b'( %s ) &' % script
+            script = b'( ( %s ) <&3 3<&- &) 3<&0' % script
             start_new_session = True
         else:
             start_new_session = False