Fix bugs with applying hunks from branch buffers (#18721)

Release Notes:

- N/A

---------

Co-authored-by: Marshall <marshall@zed.dev>

crates/text/src/text.rs

@@ -1430,16 +1430,22 @@ impl Buffer {
             counts.insert(edit_id, self.undo_map.undo_count(edit_id) + 1);
         }
 
+        let operation = self.undo_operations(counts);
+        self.history.push(operation.clone());
+        operation
+    }
+
+    pub fn undo_operations(&mut self, counts: HashMap<clock::Lamport, u32>) -> Operation {
+        let timestamp = self.lamport_clock.tick();
+        let version = self.version();
+        self.snapshot.version.observe(timestamp);
         let undo = UndoOperation {
-            timestamp: self.lamport_clock.tick(),
-            version: self.version(),
+            timestamp,
+            version,
             counts,
         };
         self.apply_undo(&undo);
-        self.snapshot.version.observe(undo.timestamp);
-        let operation = Operation::Undo(undo);
-        self.history.push(operation.clone());
-        operation
+        Operation::Undo(undo)
     }
 
     pub fn push_transaction(&mut self, transaction: Transaction, now: Instant) {