This has nothing to do with the <!–more–> tag, absolutely nothing. The code in feed-rss2.php shows the bug pretty clearly, seems the excerpt is the only text being included regardless of the option setting.
No, it’s not, it’s just that people are not actually looking at the feed and only seeing it in Firefox or whatever.
WordPress’s full text feed WORKS.
Look closer at feed-rss2.php. Here’s the relevant code:
<?php if (get_option('rss_use_excerpt')) : ?>
<description><![CDATA[<?php the_excerpt_rss() ?>]]></description>
<?php else : ?>
<description><![CDATA[<?php the_excerpt_rss() ?>]]></description>
<?php if ( strlen( $post->post_content ) > 0 ) : ?>
<content:encoded><![CDATA[<?php the_content() ?>]]></content:encoded>
<?php else : ?>
<content:encoded><![CDATA[<?php the_excerpt_rss() ?>]]></content:encoded>
<?php endif; ?>
<?php endif; ?>
That’s a complex piece of code, so let’s make it simpler, so that everybody can understand it.
if (we're using summary feeds) {
Show <description>EXCERPT HERE</description>
} else {
Show <description>EXCERPT HERE</description>
if (the post content is not empty) {
Show <content:encoded>CONTENT HERE</content:encoded>
} else {
<content:encoded>EXCERPT HERE</content:encoded>
}
}
See? The idea is that the description tag always contains the excerpt, while the content:encoded tab has the full text in it. Firefox always shows the description. Every real feed reader on the planet uses the content:encoded if/when it is available.
WordPress does NOT have a bug here. You don’t need to do any workarounds. Really. Just enable the Full Text mode in the settings. The setting works correctly and exactly as it is supposed to work.