PutIfAbsent can succeed in scattered cache on non-null entry

When the putIfAbsent is a retry, the value/metadata in RepeatableReadEntry is reset to the first loaded version. However if this command caused a prefetch from remote node after finding RemoteMetadata locally, the first loaded version is the remote metadata and the value updated by prefetch is reset, despite the prefetched value being already inserted into DC. The command sees null as cache value and since the seen version matches to the version in DC, the write is allowed.