To make kernel releases more stable/tested via "testX" series, as
recently discussed by David Miller's "Slow DOWN, please!!!" thread.
These "testX" releases will give more opportunity and time to test more
these new releases. Also, with the aim of the "testX" series, the new
kernel release schedules/merge windows will be not slow down. Even,
Linus can releases new kernels more quickly. Because, testing purpose
should be handled by someone else like Chris did for 2.6.x.y.
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