Index: trunk/src/org/openstreetmap/josm/io/CachedFile.java
===================================================================
--- trunk/src/org/openstreetmap/josm/io/CachedFile.java	(revision 19192)
+++ trunk/src/org/openstreetmap/josm/io/CachedFile.java	(revision 19194)
@@ -485,4 +485,7 @@
 
         String a = urlStr.replaceAll("[^A-Za-z0-9_.-]", "_");
+        if (a.length() > 120) {
+            a = a.substring(0, 100) + "_" + Utils.md5Hex(urlStr);
+        }
         String localPath = "mirror_" + a;
         localPath = truncatePath(destDir, localPath);