net_plugin bugfix backport of PR10349

plugins/net_plugin/net_plugin.cpp

@@ -2902,7 +2902,15 @@ namespace eosio {
          peer_requested.reset();
          flush_queues();
       } else {
-         peer_requested = peer_sync_state( msg.start_block, msg.end_block, msg.start_block-1);
+         if (peer_requested) {
+            // This happens when peer already requested some range and sync is still in progress
+            // It could be higher in case of peer requested head catchup and current request is lib catchup
+            // So to make sure peer will receive all requested blocks we assign end_block to highest value
+            peer_requested->end_block = std::max(msg.end_block, peer_requested->end_block);
+         }
+         else {
+            peer_requested = peer_sync_state( msg.start_block, msg.end_block, msg.start_block-1);
+         }
          enqueue_sync_block();
       }
    }