YARN-1617. Remove ancient comment and surround LOG.debug in AppSchedulingInfo.allocate (Sandy Ryza)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1563005 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10295. Merge change r1563019 from trunk.

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HADOOP-10317. Rename branch-2.3 release version from 2.4.0-SNAPSHOT to 2.3.0-SNAPSHOT.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1563034 13f79535-47bb-0310-9956-ffa450edef68