Index: trunk/src/org/openstreetmap/josm/data/osm/DataSetMerger.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/DataSetMerger.java	(revision 19172)
+++ trunk/src/org/openstreetmap/josm/data/osm/DataSetMerger.java	(revision 19175)
@@ -352,4 +352,5 @@
                 target.setModified(false);
             }
+            target.setReferrersDownloaded(target.isReferrersDownloaded() || source.isReferrersDownloaded());
         } else if (source.isDeleted() != target.isDeleted()) {
             // target is modified and deleted state differs.