Index: wp-includes/canonical.php
===================================================================
--- wp-includes/canonical.php	(revision 21789)
+++ wp-includes/canonical.php	(working copy)
@@ -217,9 +217,18 @@
 			$redirect_url = trailingslashit( $redirect_url ) . user_trailingslashit( get_query_var( 'page' ), 'single_paged' );
 			$redirect['query'] = remove_query_arg( 'page', $redirect['query'] );
 		}
+		
+		// check for query vars other than feed that have values that match feed slugs
+		$no_feed_vars = true;
+		foreach ( $GLOBALS['wp']->query_vars as $var => $slug ) {
+			if ( preg_match( '#feed|rss2?|rdf|atom#', $slug ) && 'feed' !== $var ) {
+				$no_feed_vars = false;
+				break;
+			}			
+		}
 
 		// paging and feeds
-		if ( get_query_var('paged') || is_feed() || get_query_var('cpage') ) {
+		if ( get_query_var('paged') || ( is_feed() && $no_feed_vars ) || get_query_var('cpage') ) {
 			while ( preg_match( "#/$wp_rewrite->pagination_base/?[0-9]+?(/+)?$#", $redirect['path'] ) || preg_match( '#/(comments/?)?(feed|rss|rdf|atom|rss2)(/+)?$#', $redirect['path'] ) || preg_match( '#/comment-page-[0-9]+(/+)?$#', $redirect['path'] ) ) {
 				// Strip off paging and feed
 				$redirect['path'] = preg_replace("#/$wp_rewrite->pagination_base/?[0-9]+?(/+)?$#", '/', $redirect['path']); // strip off any existing paging