[FIX] res.currency: allow duplication

Currencies must be unique per company.
Therefore, without this revision, adding `(Copy)`
to the currency name on duplication, this
is simply not possible to duplicate a currency.

Closes #2443

openerp/addons/base/res/res_currency.py

@@ -134,6 +134,16 @@ class res_currency(osv.osv):
         reads = self.read(cr, uid, ids, ['name','symbol'], context=context, load='_classic_write')
         return [(x['id'], tools.ustr(x['name'])) for x in reads]
 
+    def copy(self, cr, uid, id, default=None, context=None):
+        if context is None:
+            context = {}
+        if not default:
+            default = {}
+        default.update(name=_("%s (copy)")
+                       % (self.browse(cr, uid, id, context=context).name))
+        return super(res_currency, self).copy(
+            cr, uid, id, default=default, context=context)
+
     @api.v8
     def round(self, amount):
         """ Return `amount` rounded according to currency `self`. """