HBASE-7991 Backport HBASE-6479 'HFileReaderV1 caching the same parent META block could cause server abort when splitting' to 0.94



git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.94@1452465 13f79535-47bb-0310-9956-ffa450edef68