remove bogus comment

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1529648 13f79535-47bb-0310-9956-ffa450edef68
assert the IOE is correct

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1529652 13f79535-47bb-0310-9956-ffa450edef68