Undoing to the beginning of undo history causes db to be marked as unchanged

[negasora]

1. Open a file
2. Save a database
3. Rename a function
4. Rename the function again
5. Save
6. Undo once
7. Notice the database is marked as changed (you can see the dot in the tab)
8. Undo again
9. Notice the dot disappeared from the tab, and you can close the tab without being prompted to save