Some translations come with gnu getopt, but we support more languages. Therefore this patch switches to the normal JOSM I18n framework.
Index: core/src/gnu/getopt/Getopt.java
===================================================================
--- core.orig/src/gnu/getopt/Getopt.java	2012-06-18 01:11:14.320660615 +0200
+++ core/src/gnu/getopt/Getopt.java	2012-06-18 01:12:02.516661865 +0200
@@ -22,11 +22,9 @@
 
 package gnu.getopt;
 
-import static org.openstreetmap.josm.tools.I18n.tr;
-
+import java.util.Locale;
+import java.util.ResourceBundle;
 import java.text.MessageFormat;
-import java.util.HashMap;
-import java.util.Map;
 
 /**************************************************************************/
 
@@ -541,7 +539,8 @@
 /**
   * The localized strings are kept in a separate file
   */
-private OptI18n _messages = new OptI18n(); // ResourceBundle.getBundle("gnu/getopt/MessagesBundle", Locale.getDefault());
+private ResourceBundle _messages = ResourceBundle.getBundle(
+                           "gnu/getopt/MessagesBundle", Locale.getDefault());
 
 /**************************************************************************/
 
@@ -583,33 +582,6 @@
 
 /**************************************************************************/
 
-static class OptI18n {
-    public  OptI18n() {
-        add("getopt.ambigious", tr("{0}: option ''{1}'' is ambiguous"));
-        add("getopt.arguments1", tr("{0}: option ''--{1}'' does not allow an argument"));
-        add("getopt.arguments2", tr("{0}: option ''{1}{2}'' does not allow an argument"));
-        add("getopt.requires", tr("{0}: option ''{1}'' requires an argument"));
-        add("getopt.unrecognized", tr("{0}: unrecognized option ''--{1}''"));
-        add("getopt.unrecognized2", tr("{0}: unrecognized option ''{1}{2}''"));
-        add("getopt.illegal", tr("{0}: illegal option -- {1}"));
-        add("getopt.invalid", tr("{0}: invalid option -- {1}"));
-        add("getopt.requires2", tr("{0}: option requires an argument -- {1}"));
-        add("getopt.invalidValue", tr("Invalid value {0} for parameter ''has_arg''"));
-    }
-
-    Map<String, String> trns = new HashMap<String, String>();
-
-    private void add(String key, String value) {
-        trns.put(key, value);
-    }
-
-    public String getString(String s) {
-        String val = trns.get(s);
-        if (val == null) throw new IllegalArgumentException();
-        return val.replace("'", "''");
-    }
-}
-
 /**
   * Construct a Getopt instance with given input data that is capable of
   * parsing long options and short options.  Contrary to what you might
@@ -646,8 +618,8 @@
   else
     {
       posixly_correct = true;
-      _messages = new OptI18n();//ResourceBundle.getBundle("gnu/getopt/MessagesBundle",
-                             //                      Locale.US);
+      _messages = ResourceBundle.getBundle("gnu/getopt/MessagesBundle",
+                                                   Locale.US);
     }
 
   // Determine how to handle the ordering of options and non-options
Index: core/src/gnu/getopt/LongOpt.java
===================================================================
--- core.orig/src/gnu/getopt/LongOpt.java	2012-06-18 01:11:14.400660615 +0200
+++ core/src/gnu/getopt/LongOpt.java	2012-06-18 01:12:02.524661863 +0200
@@ -99,7 +99,8 @@
 /**
   * Localized strings for error messages
   */
-private Getopt.OptI18n _messages = new Getopt.OptI18n(); // ResourceBundle.getBundle("gnu/getopt/MessagesBundle", Locale.getDefault());
+private ResourceBundle _messages = ResourceBundle.getBundle(
+                            "gnu/getopt/MessagesBundle", Locale.getDefault());
 
 /**************************************************************************/