partial of PR ydb-platform#12049

Author: nshestakov

ydb/core/persqueue/partition_write.cpp

@@ -1275,6 +1275,11 @@ bool TPartition::ExecRequest(TWriteMsg& p, ProcessParameters& parameters, TEvKey
             ++WriteNewMessagesInternal;
     }
 
+    // Empty partition may will be filling from offset great than zero from mirror actor if source partition old and was clean by retantion time
+    if (!Head.GetCount() && !NewHead.GetCount() && DataKeysBody.empty() && HeadKeys.empty() && p.Offset) {
+        StartOffset = *p.Offset;
+    }
+
     TMaybe<TPartData> partData;
     if (p.Msg.TotalParts > 1) { //this is multi-part message
         partData = TPartData(p.Msg.PartNo, p.Msg.TotalParts, p.Msg.TotalSize);