--- a/rust/hg-core/src/dirstate_tree/on_disk.rs	Fri Nov 26 15:07:59 2021 +0100
+++ b/rust/hg-core/src/dirstate_tree/on_disk.rs	Mon Nov 29 17:37:08 2021 +0100
@@ -553,7 +553,7 @@
 /// `dirstate_map.on_disk` (true), instead of written to a new data file
 /// (false).
 pub(super) fn write(
-    dirstate_map: &mut DirstateMap,
+    dirstate_map: &DirstateMap,
     can_append: bool,
 ) -> Result<(Vec<u8>, Vec<u8>, bool), DirstateError> {
     let append = can_append && dirstate_map.write_should_append();