Index: trunk/src/org/openstreetmap/josm/gui/tagging/ac/AutoCompletingTextField.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/tagging/ac/AutoCompletingTextField.java	(revision 8266)
+++ trunk/src/org/openstreetmap/josm/gui/tagging/ac/AutoCompletingTextField.java	(revision 8267)
@@ -8,4 +8,5 @@
 import java.awt.event.KeyEvent;
 import java.util.EventObject;
+import java.util.Objects;
 
 import javax.swing.ComboBoxEditor;
@@ -95,5 +96,5 @@
             String prefix = currentText.substring(0, offs);
             autoCompletionList.applyFilter(prefix+str);
-            if (autoCompletionList.getFilteredSize()>0) {
+            if (autoCompletionList.getFilteredSize() > 0 && !Objects.equals(str, noAutoCompletionString)) {
                 // there are matches. Insert the new text and highlight the
                 // auto completed suffix
@@ -120,4 +121,6 @@
     /** the auto completion list user input is matched against */
     protected AutoCompletionList autoCompletionList = null;
+    /** a string which should not be auto completed */
+    protected String noAutoCompletionString = null;
 
     @Override
@@ -219,4 +222,11 @@
     }
 
+    @Override
+    public void setText(String t) {
+        // disallow auto completion for this explicitly set string
+        this.noAutoCompletionString = t;
+        super.setText(t);
+    }
+
     /**
      * Sets the maximum number of characters allowed.