Merge -r 1450722:1450723 from trunk to branch-2. Fixes: MAPREDUCE-5008. Merger progress miscounts with respect to EOF_MARKER. Contributed by Sandy Ryza.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1450724 13f79535-47bb-0310-9956-ffa450edef68