--- a/mercurial/helptext/config.txt	Wed Jan 13 23:07:41 2021 +0100
+++ b/mercurial/helptext/config.txt	Wed Jan 13 23:41:37 2021 +0100
@@ -904,8 +904,11 @@
     operation for larger repository.
 
     The performance improving version of this feature is currently only
-    implemented in Rust, so people using a version of Mercurial compiled
-    without the Rust part might actually suffer some slowdown.
+    implemented in Rust, so people not using a version of Mercurial compiled
+    with the Rust part  might actually suffer some slowdown. For this reason,
+    Such version will by default refuse to access such repositories. That
+    behavior can be controlled by configuration. Check
+    :hg:`help config.storage.revlog.persistent-nodemap.slowpath` for details.
 
     Repository with this on-disk format require Mercurial version 5.4 or above.
 
@@ -1960,8 +1963,7 @@
 
     ``allow``: Silently use the slower implementation to access the repository.
     ``warn``: Warn, but use the slower implementation to access the repository.
-
-    Default to ``warn``
+    ``abort``: Prevent access to such repositories. (This is the default)
 
     For details on the "persistent-nodemap" feature, see:
     :hg:`help config format.use-persistent-nodemap`.