Exporting a page to PDF is currently broken

This affects the latest head as of 27-Nov 12pm.

The stack produced:

2003-11-27 12:00:42,631 ERROR [confluence.importexport.impl.AbstractRendererExporterImpl$1] Can not transform XHTML to XSL-FO due to an error!
javax.xml.transform.TransformerException: org.w3c.dom.DOMException: `null' prefix expects a namespace uri
at org.apache.xalan.templates.ElemLiteralResult.execute(ElemLiteralResult.java:725)
at org.apache.xalan.templates.ElemApplyTemplates.transformSelectedNodes(ElemApplyTemplates.java:425)
at org.apache.xalan.templates.ElemApplyTemplates.execute(ElemApplyTemplates.java:216)
at org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(TransformerImpl.java:2339)
at org.apache.xalan.transformer.TransformerImpl.applyTemplateToNode(TransformerImpl.java:2160)
at org.apache.xalan.transformer.TransformerImpl.transformNode(TransformerImpl.java:1213)
at org.apache.xalan.transformer.TransformerImpl.transform(TransformerImpl.java:668)
at org.apache.xalan.transformer.TransformerImpl.transform(TransformerImpl.java:1129)
at org.apache.xalan.transformer.TransformerImpl.transform(TransformerImpl.java:1107)
at com.atlassian.confluence.importexport.impl.WikiExporter.convertXHtmlToXslFo(WikiExporter.java:133)
at com.atlassian.confluence.importexport.impl.WikiExporter.exportWikiToXslFo(WikiExporter.java:88)
at com.atlassian.confluence.importexport.impl.PdfExporter.convertWikiToXslFo(PdfExporter.java:151)
at com.atlassian.confluence.importexport.impl.PdfExporter.prepareExportTemplate(PdfExporter.java:134)
at com.atlassian.confluence.importexport.impl.PdfExporter.prepareExportXSLFo(PdfExporter.java:264)
at com.atlassian.confluence.importexport.impl.PdfExporter.doExportEntity(PdfExporter.java:165)
at com.atlassian.confluence.importexport.impl.AbstractRendererExporterImpl.exportPage(AbstractRendererExporterImpl.java:142)
at com.atlassian.confluence.importexport.impl.AbstractRendererExporterImpl.doExport(AbstractRendererExporterImpl.java:108)
at com.atlassian.confluence.importexport.impl.PdfExporter.doExport(PdfExporter.java:82)
at com.atlassian.confluence.importexport.DefaultImportExportManager.exportAs(DefaultImportExportManager.java:102)
at com.atlassian.confluence.importexport.actions.ExportPageAction.execute(ExportPageAction.java:78)