HTML export is broken

java.lang.StringIndexOutOfBoundsException: String index out of range: -1
        at java.lang.String.substring(String.java:1762)
        at java.lang.String.substring(String.java:1735)
        at com.xpn.xwiki.render.XWikiVelocityRenderer.getVelocityEngine(XWikiVelocityRenderer.java:126)
        at com.xpn.xwiki.render.XWikiVelocityRenderer.evaluate(XWikiVelocityRenderer.java:200)
        at com.xpn.xwiki.XWiki.parseTemplate(XWiki.java:1496)
        at com.xpn.xwiki.export.html.HtmlPackager.renderDocument(HtmlPackager.java:172)
        at com.xpn.xwiki.export.html.HtmlPackager.renderDocuments(HtmlPackager.java:210)
        at com.xpn.xwiki.export.html.HtmlPackager.export(HtmlPackager.java:249)
        at com.xpn.xwiki.web.ExportAction.exportHTML(ExportAction.java:170)
        at com.xpn.xwiki.web.ExportAction.render(ExportAction.java:59)
        at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:205)
        at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
        at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
        at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
        at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:596)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
        at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:428)
        at org.mortbay.jetty.servlet.WebApplicationHandler$CachedChain.doFilter(WebApplicationHandler.java:830)
        at com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:112)
        at org.mortbay.jetty.servlet.WebApplicationHandler$CachedChain.doFilter(WebApplicationHandler.java:821)
        at org.mortbay.jetty.servlet.WebApplicationHandler.dispatch(WebApplicationHandler.java:471)
        at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:568)
        at org.mortbay.http.HttpContext.handle(HttpContext.java:1565)
        at org.mortbay.jetty.servlet.WebApplicationContext.handle(WebApplicationContext.java:633)
        at org.mortbay.http.HttpContext.handle(HttpContext.java:1517)
        at org.mortbay.http.HttpServer.service(HttpServer.java:954)
        at org.mortbay.http.HttpConnection.service(HttpConnection.java:816)
        at org.mortbay.http.HttpConnection.handleNext(HttpConnection.java:983)
        at org.mortbay.http.HttpConnection.handle(HttpConnection.java:833)
        at org.mortbay.http.SocketListener.handleConnection(SocketListener.java:244)
        at org.mortbay.util.ThreadedServer.handle(ThreadedServer.java:357)
        at org.mortbay.util.ThreadPool$PoolThread.run(ThreadPool.java:534)