LUCENE-5904: fix test to make empty initial commit

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1621421 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5904: fix redundant cast warning

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1621424 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5904: fix false fail

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1621428 13f79535-47bb-0310-9956-ffa450edef68
don't let virus checker run when testing merge stability

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1621433 13f79535-47bb-0310-9956-ffa450edef68