HBASE-9926 Scanner doesn't check if a region is available

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.96@1540887 13f79535-47bb-0310-9956-ffa450edef68
HBASE-9952 Snapshot restore may fail due to NullPointerException

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.96@1540911 13f79535-47bb-0310-9956-ffa450edef68