--- a/rust/hg-core/src/dirstate_tree/status.rs	Tue Oct 12 16:20:05 2021 +0200
+++ b/rust/hg-core/src/dirstate_tree/status.rs	Tue Oct 12 16:38:13 2021 +0200
@@ -1,4 +1,4 @@
-use crate::dirstate::entry::Timestamp;
+use crate::dirstate::entry::TruncatedTimestamp;
 use crate::dirstate::status::IgnoreFnType;
 use crate::dirstate_tree::dirstate_map::BorrowedPath;
 use crate::dirstate_tree::dirstate_map::ChildNodesRef;
@@ -126,7 +126,8 @@
     matcher: &'a (dyn Matcher + Sync),
     ignore_fn: IgnoreFnType<'a>,
     outcome: Mutex<DirstateStatus<'on_disk>>,
-    new_cachable_directories: Mutex<Vec<(Cow<'on_disk, HgPath>, Timestamp)>>,
+    new_cachable_directories:
+        Mutex<Vec<(Cow<'on_disk, HgPath>, TruncatedTimestamp)>>,
     outated_cached_directories: Mutex<Vec<Cow<'on_disk, HgPath>>>,
 
     /// Whether ignore files like `.hgignore` have changed since the previous
@@ -165,7 +166,7 @@
         dirstate_node: &NodeRef<'tree, 'on_disk>,
     ) -> Result<(), DirstateV2ParseError> {
         if self.ignore_patterns_have_changed == Some(true)
-            && dirstate_node.cached_directory_mtime().is_some()
+            && dirstate_node.cached_directory_mtime()?.is_some()
         {
             self.outated_cached_directories.lock().unwrap().push(
                 dirstate_node
@@ -182,7 +183,7 @@
     fn can_skip_fs_readdir(
         &self,
         directory_metadata: Option<&std::fs::Metadata>,
-        cached_directory_mtime: Option<Timestamp>,
+        cached_directory_mtime: Option<TruncatedTimestamp>,
     ) -> bool {
         if !self.options.list_unknown && !self.options.list_ignored {
             // All states that we care about listing have corresponding
@@ -199,8 +200,9 @@
                 // directory eligible for `read_dir` caching.
                 if let Some(meta) = directory_metadata {
                     if let Ok(current_mtime) = meta.modified() {
-                        let current_mtime = Timestamp::from(current_mtime);
-                        if current_mtime == cached_mtime {
+                        let truncated =
+                            TruncatedTimestamp::from(current_mtime);
+                        if truncated.very_likely_equal(&cached_mtime) {
                             // The mtime of that directory has not changed
                             // since then, which means that the results of
                             // `read_dir` should also be unchanged.
@@ -222,7 +224,7 @@
         directory_hg_path: &BorrowedPath<'tree, 'on_disk>,
         directory_fs_path: &Path,
         directory_metadata: Option<&std::fs::Metadata>,
-        cached_directory_mtime: Option<Timestamp>,
+        cached_directory_mtime: Option<TruncatedTimestamp>,
         is_at_repo_root: bool,
     ) -> Result<bool, DirstateV2ParseError> {
         if self.can_skip_fs_readdir(directory_metadata, cached_directory_mtime)
@@ -363,7 +365,7 @@
                     hg_path,
                     fs_path,
                     Some(fs_metadata),
-                    dirstate_node.cached_directory_mtime(),
+                    dirstate_node.cached_directory_mtime()?,
                     is_at_repo_root,
                 )?;
             self.maybe_save_directory_mtime(
@@ -466,16 +468,22 @@
                     //
                     // We deem this scenario (unlike the previous one) to be
                     // unlikely enough in practice.
-                    let timestamp = directory_mtime.into();
-                    let cached = dirstate_node.cached_directory_mtime();
-                    if cached != Some(timestamp) {
+                    let truncated = TruncatedTimestamp::from(directory_mtime);
+                    let is_up_to_date = if let Some(cached) =
+                        dirstate_node.cached_directory_mtime()?
+                    {
+                        cached.very_likely_equal(&truncated)
+                    } else {
+                        false
+                    };
+                    if !is_up_to_date {
                         let hg_path = dirstate_node
                             .full_path_borrowed(self.dmap.on_disk)?
                             .detach_from_tree();
                         self.new_cachable_directories
                             .lock()
                             .unwrap()
-                            .push((hg_path, timestamp))
+                            .push((hg_path, truncated))
                     }
                 }
             }