Regression: Inconsistent behavior when renaming cpp-file

1. Open a Qt GUI Application project.
2. Rename a source file to contain capital letters only using "Rename..." in the "Projects" view's context menu, e.g. rename "main.cpp" to "MAIN.CPP".
   The file will move from "Sources" to "Headers".
3. Open project declarative-music-browser from "Examples/QtMobility" from a Qt 4 SDK.
4. Repeat step 2 in this project.
   The file will move from "Sources" to "Other files".

I think a CPP-file should still be treated as a source file. If this can't be done for some reason, the behavior should at least be consistent across projects. This used to work in 2.8.

Found by Squish test tst_rename_file.