diff mercurial/localrepo.py @ 50798:f0ae403bf704

configitems: use standard "dynamicdefault" approach in edge case

This makes for fewer edge cases, which will help a future patch.

--- a/mercurial/localrepo.py	Tue Jan 17 14:53:18 2023 +0100
+++ b/mercurial/localrepo.py	Mon Jan 23 17:21:14 2023 +0100
@@ -58,6 +58,7 @@
     obsolete,
     pathutil,
     phases,
+    policy,
     pushkey,
     pycompat,
     rcutil,
@@ -3763,7 +3764,11 @@
     if ui.configbool(b'format', b'bookmarks-in-store'):
         requirements.add(requirementsmod.BOOKMARKS_IN_STORE_REQUIREMENT)
 
-    if ui.configbool(b'format', b'use-persistent-nodemap'):
+    # The feature is disabled unless a fast implementation is available.
+    persistent_nodemap_default = policy.importrust('revlog') is not None
+    if ui.configbool(
+        b'format', b'use-persistent-nodemap', persistent_nodemap_default
+    ):
         requirements.add(requirementsmod.NODEMAP_REQUIREMENT)
 
     # if share-safe is enabled, let's create the new repository with the new