Hello, igniters. Can you look it? My solution is to save a snapshot of
txState when user calls tx.savepoint("id") and replace current txState with
saved state when user calls tx.rollbackToSavepoint("id").JIRA: https://issues.apache.org/jira/browse/IGNITE-4188 PR: https://github.com/apache/ignite/pull/1815/files
