Bug 148747 Design become invalid when I extend a masterpage from Library
The attachment contains a report file and a library file. Reproduce: 1. Deploy the library("lib"), and open the report. 2. Drag Masterpage("page1") from "lib" to report. 3. Reopen the report, it become invalid.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/parser/ReportElementState.java
{
		Iterator contentIter = new ContentIterator( element );
		Module module = handler.getModule( );
		while ( contentIter.hasNext( ) )
		{
			DesignElement virtualElement = (DesignElement) contentIter.next( );
			if ( virtualElement.getName( ) != null )
			{
				module.makeUniqueName( virtualElement );
				addToNamespace( virtualElement );
			}
		}
	}
	/**
	 * Parse the attribute of "extensionName" for extendable element.
	 * 
	 * @param attrs
	 *            the SAX attributes object
	 * @param extensionNameRequired
	 *            whether extension name is required
	 */
	protected void parseExtensionName( Attributes attrs,
			boolean extensionNameRequired )
	{
		DesignElement element = getElement( );
		assert element instanceof IExtendableElement;
		String extensionName = getAttrib( attrs,
				DesignSchemaConstants.EXTENSION_NAME_ATTRIB );
		if ( StringUtil.isBlank( extensionName ) )
		{