>In 1997, a group of developers formed EGCS (Experimental/Enhanced GNU Compiler System),[14] to merge several experimental forks into a single project. The basis of the merger was a GCC development snapshot taken between the 2.7 and 2.81 releases. Projects merged included g77 (FORTRAN), PGCC (P5 Pentium-optimized GCC), many C++ improvements, and many new architectures and operating system variants.[15][16]
>EGCS development proved considerably more vigorous than GCC development, so much so that the FSF officially halted development on their GCC 2.x compiler, "blessed" EGCS as the official version of GCC and appointed the EGCS project as the GCC maintainers in April 1999. Furthermore, the project explicitly adopted the "bazaar" model over the "cathedral" model. With the release of GCC 2.95 in July 1999, the two projects were once again united.

Внезапно, пример. Только не тот, что Вы просили, а пример обратного — существования форка, причем оказавшегося настолько лучше официального, что официальный забросили, а новым официальным обьявили форк.