[REG 3.5.0 -> 3.6.0] "Rename File" has different result when you do it again

1. Create a new Qt Widgets Application project.
2. Open the project's main.cpp.
3. At the beginning of the file, insert the attached header. It's taken from an old example project.
4. Save and close all files.
5. Right-click on main.cpp in Projects view and rename it to "test".
   It moves to "Other files" (QTCREATORBUG-14469).
6. Oops, wrong file name. Rename it back to "main.cpp".
   The file moves back to "Sources"
7. Oops, now this was wrong. Rename it to "test" again.
   Now the file is gone.

Creator should not lose track of files during renaming. In addition, whatever happens during renaming should always be the same. Having different reactions to the same actions is broken behavior.

In Creator 3.5, this used to work correctly.

Found by Squish test tst_rename_file