Index: /trunk/src/org/openstreetmap/josm/io/auth/CredentialsManager.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/io/auth/CredentialsManager.java	(revision 4263)
+++ /trunk/src/org/openstreetmap/josm/io/auth/CredentialsManager.java	(revision 4264)
@@ -87,5 +87,5 @@
     @Override
     public void store(RequestorType requestorType, PasswordAuthentication credentials) throws CredentialsAgentException {
-        if (requestorType == RequestorType.SERVER && credentials.getUserName() != null) {
+        if (requestorType == RequestorType.SERVER && credentials.getUserName() != null && !credentials.getUserName().trim().isEmpty()) {
             JosmUserIdentityManager.getInstance().setPartiallyIdentified(credentials.getUserName());
         }