Steps to reproduce:
1. Create a new project
2. Create a new C# script, name it "test"
3. Create a new gameObject in the hierarchy
4. Attach "test" script to that gameObject
5. Open "test" script with MonoDevelop
6. Right click on class name in the script and press Refactor\Rename
7. Rename the class
8. Save and close monoDevelop
9. Select gameObject you craeted before in the Hierarchy
10. Notice how it lost script reference

Expected behavior: script reference is not lost when renaming a class

Reproduced with: 5.2.4f1, 5.3.6f1, 5.4.0f2