fs: a rename of the open file itself no longer drops the staged write

The pending commit moved to `to.join("")`, which has a trailing slash, so
the commit rename failed and the staged file was deleted.

cli/src/fs.rs

@@ -339,8 +339,12 @@ impl HostDescriptor for ActorFs<'_> {
         HostDescriptor::rename_at(&mut self.inner, fd, old_path, new_fd, new_path).await?;
         // Open writes and directories below a renamed folder move with it.
         if let Some((from, to)) = moved {
+            // `join("")` would add a trailing slash, so a renamed file itself
+            // needs its own case.
             let rebase = |p: &mut PathBuf| {
-                if let Ok(rest) = p.strip_prefix(&from) {
+                if *p == from {
+                    *p = to.clone();
+                } else if let Ok(rest) = p.strip_prefix(&from) {
                     *p = to.join(rest);
                 }
             };

cli/tests/host.rs

@@ -776,6 +776,21 @@ async fn close_commits_open_file_after_parent_directory_rename() {
     host.stop().await;
 }
 
+#[tokio::test]
+async fn close_commits_a_staged_write_after_the_file_itself_is_renamed() {
+    let (_, host, mut mailbox) = filesystem_world("rename-staged-file").await;
+    let write = json!({"type": "write", "path": "/data/x", "text": "old"});
+    ask_type(&host, &mut mailbox, "writer", write, "ok").await;
+    let open = json!({"type": "open-truncate", "path": "/data/x", "text": "new"});
+    ask_type(&host, &mut mailbox, "writer", open, "opened").await;
+    let rename = json!({"type": "rename", "path": "/data/x", "to": "/data/x.renamed"});
+    ask_type(&host, &mut mailbox, "writer", rename, "ok").await;
+    ask_type(&host, &mut mailbox, "writer", json!({"type": "close", "path": "/data/x"}), "closed").await;
+    let read = json!({"type": "read", "path": "/data/x.renamed"});
+    assert_eq!(ask_type(&host, &mut mailbox, "writer", read, "content").await.body["text"], "new");
+    host.stop().await;
+}
+
 #[tokio::test]
 async fn truncate_without_create_commits_existing_file_on_close() {
     let (_, host, mut mailbox) = filesystem_world("truncate-without-create").await;