Index: wp-includes/link-template.php
===================================================================
--- wp-includes/link-template.php	(revision 5044)
+++ wp-includes/link-template.php	(working copy)
@@ -421,73 +421,54 @@
 
 function get_pagenum_link($pagenum = 1) {
 	global $wp_rewrite;
+	$pagenum = (int) $pagenum;
 
-	$qstr = wp_specialchars($_SERVER['REQUEST_URI']);
+	// grab the qs from REQUEST_URI and remove any existing ?paged=X
+	$request = remove_query_arg('paged');
 
+/*
 	$page_querystring = "paged";
 	$page_modstring = "page/";
 	$page_modregex = "page/?";
 	$permalink = 0;
+*/
 
+
 	$home_root = parse_url(get_option('home'));
 	$home_root = $home_root['path'];
-	$home_root = trailingslashit($home_root);
-	$qstr = preg_replace('|^'. $home_root . '|', '', $qstr);
-	$qstr = preg_replace('|^/+|', '', $qstr);
+	$home_root = preg_quote(trailingslashit($home_root), '|');
+	$request = preg_replace('|^'. $home_root . '|', '', $request);
+	$request = preg_replace('|^/+|', '', $request);
 
-	$index = $_SERVER['PHP_SELF'];
-	$index = preg_replace('|^'. $home_root . '|', '', $index);
-	$index = preg_replace('|^/+|', '', $index);
-
-	// if we already have a QUERY style page string
-	if ( stristr( $qstr, $page_querystring ) ) {
-		$replacement = "$page_querystring=$pagenum";
-		$qstr = preg_replace("/".$page_querystring."[^\d]+\d+/", $replacement, $qstr);
-		// if we already have a mod_rewrite style page string
-	} elseif ( preg_match( '|'.$page_modregex.'\d+|', $qstr ) ) {
-		$permalink = 1;
-		$qstr = preg_replace('|'.$page_modregex.'\d+|',"$page_modstring$pagenum",$qstr);
-
-		// if we don't have a page string at all ...
-		// lets see what sort of URL we have...
+	if ( !$wp_rewrite->using_permalinks() ) {
+		$base = trailingslashit($get_option('home'));
+		if ( $pagenum > 1 )
+			$result = $base . add_query_arg('paged', $pagenum, $request);
+		else
+			$result = $base . $request;
 	} else {
-		// we need to know the way queries are being written
-		// if there's a querystring_start (a "?" usually), it's definitely not mod_rewritten
-		if ( stristr( $qstr, '?' ) ) {
-			// so append the query string (using &, since we already have ?)
-			$qstr .=	'&' . $page_querystring . '=' . $pagenum;
-			// otherwise, it could be rewritten, OR just the default index ...
-		} elseif( '' != get_option('permalink_structure') && ! is_admin() ) {
-			$permalink = 1;
-			$index = $wp_rewrite->index;
-			// If it's not a path info permalink structure, trim the index.
-			if ( !$wp_rewrite->using_index_permalinks() ) {
-				$qstr = preg_replace("#/*" . $index . "/*#", '/', $qstr);
-			} else {
-				// If using path info style permalinks, make sure the index is in
-				// the URL.
-				if ( strpos($qstr, $index) === false )
-					$qstr = '/' . $index . $qstr;
-			}
-
-			$qstr =	trailingslashit($qstr) . $page_modstring . $pagenum;
+		$qs_regex = '|\?.*?$|';
+		preg_match($qs_regex, $request, $qs_match);
+		if ( $qs_match[0] ) {
+			$query_string = $qs_match[0];
+			$request = preg_replace($qs_regex, '', $request);
 		} else {
-			$qstr = $index . '?' . $page_querystring . '=' . $pagenum;
+			$query_string = '';
 		}
-	}
 
-	$qstr = preg_replace('|^/+|', '', $qstr);
-	if ( $permalink )
-		$qstr = user_trailingslashit($qstr, 'paged');
-	$qstr = preg_replace('/&([^#])(?![a-z]{1,8};)/', '&$1', trailingslashit( get_option('home') ) . $qstr );
+		// clean /index.php [...] /page/N/ or variants
+		$request = preg_replace('|^/?index\.php/?|', '', $request);
+		$request = preg_replace('|/?page/[0-9]*?/?$|', '', $request);
 
-	// showing /page/1/ or ?paged=1 is redundant
-	if ( 1 === $pagenum ) {
-		$qstr = str_replace(user_trailingslashit('index.php/page/1', 'paged'), '', $qstr); // for PATHINFO style
-		$qstr = str_replace(user_trailingslashit('page/1', 'paged'), '', $qstr); // for mod_rewrite style
-		$qstr = remove_query_arg('paged', $qstr); // for query style
+		$base = get_option('home') . '/';
+		if ( $wp_rewrite->using_index_permalinks() && $pagenum > 1 )
+			$base .= 'index.php/';
+		$request = ( $pagenum > 1 ) ? $request . user_trailingslashit('page/' . $pagenum, 'paged') : $request;
+		$result = $base . $request . $query_string;
+
 	}
-	return $qstr;
+
+	return $result;
 }
 
 function next_posts($max_page = 0) { // original by cfactor at cooltux.org