WordPress：需要更改RSS Feed中的帖子永久链接URL

For some reason, I need a slight change in the URLs that go out with the RSS feed of my WP-powered blog. Currently, the permalinks look like this:

http://www.thesite.com/blogs/post_title

This is the URL that's going into my RSS feed (a custom feed I built) as well. However, I need the URL to go with blog instead of blogs:

http://www.thesite.com/blog/post_title

To that end, this is what I tried using the str_replace() function with WP's the_permalink_rss() in my custom feed PHP (rss-burrofeed.php) code and here's the snippet illustrating this hack in context:

   <item>
        <title><?php the_title_rss(); ?></title>
        <link><?php str_replace('/blogs/','/blog/',the_permalink()); ?></link>
        <pubDate><?php echo mysql2date('D, d M Y H:i:s +0000', get_post_time('Y-m-d H:i:s', true), false); ?></pubDate>
         <dc:creator><?php the_author(); ?></dc:creator>
         <guid isPermaLink="false"><?php the_guid(); ?></guid>
         <description><![CDATA[<?php the_excerpt_rss() ?>]]></description>
         <content:encoded><![CDATA[<?php the_excerpt_rss() ?>]]></content:encoded>
         <?php rss_enclosure(); ?>
         <?php do_action('rss2_item'); ?>
</item>

But this is not working. The links are still appearing with blogs and not blog. Am I doing something wrong? Why isn't str_replace() working?

Is posible than the function the_permalink() is generate other info, because I try and found me

    $phrase  = "http://www.thesite.com/blogs/post_title";
    $newphrase = str_replace('/blogs/','/blog/',$phrase);

    print_R($phrase);
    print_R('<br>');
    print_R($newphrase);

and print:

http://www.thesite.com/blogs/post_title
http://www.thesite.com/blog/post_title

the parameter is string, I think than the function dont give data equal!