diff -r c577bb4a04d4 -r 5962fd0d1045 mercurial/localrepo.py
--- a/mercurial/localrepo.py	Wed Jan 15 15:47:12 2020 +0100
+++ b/mercurial/localrepo.py	Wed Jan 15 15:47:21 2020 +0100
@@ -932,6 +932,8 @@
 
     if ui.configbool(b'experimental', b'rust.index'):
         options[b'rust.index'] = True
+    if ui.configbool(b'experimental', b'exp-persistent-nodemap'):
+        options[b'exp-persistent-nodemap'] = True
 
     return options