Error in log when importing default XAR in an empty wiki

2010-12-23 21:19:31,607 [Lucene Index Updater] WARN  lucene.AttachmentData           - error getting content of attachment [xwiki-enterprise-wiki-2.7.xar] for document [xwiki:XWiki.XWikiPreferences] 
java.lang.NullPointerException
        at com.xpn.xwiki.plugin.lucene.AttachmentData.getContentAsText(AttachmentData.java:161)
        at com.xpn.xwiki.plugin.lucene.AttachmentData.getFullText(AttachmentData.java:136)
        at com.xpn.xwiki.plugin.lucene.IndexData.getFullText(IndexData.java:190)
        at com.xpn.xwiki.plugin.lucene.IndexData.addDataToLuceneDocument(IndexData.java:146)
        at com.xpn.xwiki.plugin.lucene.AttachmentData.addDataToLuceneDocument(AttachmentData.java:65)
        at com.xpn.xwiki.plugin.lucene.IndexUpdater.addToIndex(IndexUpdater.java:296)
        at com.xpn.xwiki.plugin.lucene.IndexUpdater.updateIndex(IndexUpdater.java:237)
        at com.xpn.xwiki.plugin.lucene.IndexUpdater.runMainLoop(IndexUpdater.java:171)
        at com.xpn.xwiki.plugin.lucene.IndexUpdater.runInternal(IndexUpdater.java:153)
        at com.xpn.xwiki.util.AbstractXWikiRunnable.run(AbstractXWikiRunnable.java:99)
        at java.lang.Thread.run(Thread.java:680)