Index: /trunk/src/org/openstreetmap/josm/tools/HttpClient.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/tools/HttpClient.java	(revision 14521)
+++ /trunk/src/org/openstreetmap/josm/tools/HttpClient.java	(revision 14522)
@@ -161,5 +161,9 @@
                 );
                 if (Logging.isDebugEnabled()) {
-                    Logging.debug("RESPONSE: {0}", connection.getHeaderFields());
+                    try {
+                        Logging.debug("RESPONSE: {0}", connection.getHeaderFields());
+                    } catch (IllegalArgumentException e) {
+                        Logging.warn(e);
+                    }
                 }
                 if (DefaultAuthenticator.getInstance().isEnabled() && connection.getResponseCode() == HttpURLConnection.HTTP_UNAUTHORIZED) {
Index: /trunk/test/unit/org/openstreetmap/josm/gui/preferences/imagery/ImageryPreferenceTestIT.java
===================================================================
--- /trunk/test/unit/org/openstreetmap/josm/gui/preferences/imagery/ImageryPreferenceTestIT.java	(revision 14521)
+++ /trunk/test/unit/org/openstreetmap/josm/gui/preferences/imagery/ImageryPreferenceTestIT.java	(revision 14522)
@@ -65,5 +65,5 @@
 
     private void checkUrl(ImageryInfo info, String url) {
-        if (url != null && !workingURLs.contains(url)) {
+        if (url != null && !url.isEmpty() && !workingURLs.contains(url)) {
             try {
                 Response response = HttpClient.create(new URL(url)).connect();