$this->migrateToTemp(
'revision', 'rev_id', 'rev_comment', 'revcomment_rev', 'revcomment_comment_id'
);
$this->migrate( 'archive', 'ar_id', 'ar_comment' );
$this->migrate( 'ipblocks', 'ipb_id', 'ipb_reason' );
$this->migrateToTemp(
'revision', 'rev_id', 'rev_comment', 'revcomment_rev', 'revcomment_comment_id'
);
$this->migrate( 'archive', 'ar_id', 'ar_comment' );
$this->migrate( 'ipblocks', 'ipb_id', 'ipb_reason' );