YARN-2171. Improved CapacityScheduling to not lock on nodemanager-count when AMs heartbeat in. Contributed by Jason Lowe.
svn merge --ignore-ancestry -c 1605616 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1605617 13f79535-47bb-0310-9956-ffa450edef68