SOLR-6529: Stop command in the start scripts should only stop the instance that it had started

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_5x@1630607 13f79535-47bb-0310-9956-ffa450edef68
SOLR-5986: Fix tests and start returning partial results in case of ExitingReaderException (Merge from trunk r1630583)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_5x@1630611 13f79535-47bb-0310-9956-ffa450edef68