I merged gcc-4.2.2 today, and found there are two files collision.
These two files belong to not only gcc-4.2.0 but also gcc-4.2.2. After I unmerge gcc-4.2.0, I checked files belonging to gcc-4.2.2, the 2 files did lost(only the 2 files lost). Luckly I had backup them before unmerge gcc-4.2.0, so I need not remerge gcc-4.2.2 again.
*** This bug has been marked as a duplicate of bug 136382 ***