Bug 760398 - Cancelling the creation of a duplicate bill or invoice d…

…oesn't reset the invoice number counter

Don't set the invoice ID before the user has clicked OK in the dialog.
If the user cancels in the dialog the counter would have already been
incrementd. Making the ID an empty string makes the ID be set in
gnc_invoice_window_verify_ok().

src/business/business-gnome/dialog-invoice.c

@@ -2697,7 +2697,6 @@ InvoiceWindow * gnc_ui_invoice_duplicate (GncInvoice *old_invoice, gboolean open
 {
     InvoiceWindow *iw;
     GncInvoice *new_invoice = NULL;
-    gchar *new_id;
     GDate new_date_gdate;
 
     g_assert(old_invoice);
@@ -2718,11 +2717,8 @@ InvoiceWindow * gnc_ui_invoice_duplicate (GncInvoice *old_invoice, gboolean open
         }
     }
 
-    // Set a new id from the respective counter
-    new_id = gncInvoiceNextID(gnc_get_current_book(),
-                              gncInvoiceGetOwner(new_invoice));
-    gncInvoiceSetID(new_invoice, new_id);
-    g_free(new_id);
+    // Unset the invoice ID, let it get allocated later
+    gncInvoiceSetID(new_invoice, "");
 
     // Modify the date to today
     if (new_date)