FELIX-541: preserve prolog in existing repository documents

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@650848 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/bundleplugin/src/main/java/org/apache/felix/obrplugin/ObrUpdate.java b/bundleplugin/src/main/java/org/apache/felix/obrplugin/ObrUpdate.java
index fdb34e9..b30ebcd 100644
--- a/bundleplugin/src/main/java/org/apache/felix/obrplugin/ObrUpdate.java
+++ b/bundleplugin/src/main/java/org/apache/felix/obrplugin/ObrUpdate.java
@@ -265,7 +265,7 @@
     {
         m_logger.info( "Writing OBR metadata" );
 
-        writeToFile( m_repositoryXml, m_repositoryDoc.getDocumentElement() );
+        writeToFile( m_repositoryXml, m_repositoryDoc );
     }