Please check PageRenamer.java, where line 113 should NOT be called before getReferrersCollection().

Here is a snapshot:

m_wikiEngine.getReferenceManager().clearPageEntries(oldName);


// Get the collection of pages that the refered to the old name (the From name)...
Collection referrers = getReferrersCollection( oldName );

// If there were pages refering to the old name, update them to point to the new name...
if( referrers != null )
{
     updateReferrersOnRename( oldName, newName, changeReferrers, newNameCleaned, referrers );
}
else
{
     // XXX: Questionable behaviour!
     m_wikiEngine.initReferenceManager();
}

So, reffers always be null.

BTW, code m_wikiEngine.getReferenceManager().clearPageEntries(oldName); is called in the updateReferrersOnRename() method.

Fixed in the current CVS.