diff -r 8f07f5a9c3de -r 21733e8c924f mercurial/configitems.py
--- a/mercurial/configitems.py	Sat Nov 07 21:50:28 2020 -0800
+++ b/mercurial/configitems.py	Wed Oct 21 19:00:16 2020 -0700
@@ -1307,6 +1307,9 @@
     b'ui', b'editor', default=dynamicdefault,
 )
 coreconfigitem(
+    b'ui', b'detailed-exit-code', default=False, experimental=True,
+)
+coreconfigitem(
     b'ui', b'fallbackencoding', default=None,
 )
 coreconfigitem(