[SPARK-2815]: Compilation failed upon the hadoop version 2.0.0-cdh4.5.0

If there is ever a Hadoop 2.10, this pattern would consider it a YARN alpha version. Better to match against `2\\.[01]\\.[0-9]+` or something. This won't address the actual issue in the OP. It looks like a bit of cleanup, but in a deprecated code path. It would let Hadoop 2.0 / 2.1 be "supported" but they aren't actually.