There are no false positives in the Core File Changes scan. The contents of that file has certainly been altered from it’s original form. You or your developers may have modified that file and a Core File Change does not necessarily mean that it was modified maliciously, but it is unwise to modify WP Core Files and your theme changes should never effect the Core Files. You can click on this listing in my plugin’s results to see the contents and click on the  to see what lines have been modified. If you made these changes yourself then you can decide to keep the changes but I would recommend restoring the original file.