Index: wp-includes/rewrite.php
===================================================================
--- wp-includes/rewrite.php	(revision 18459)
+++ wp-includes/rewrite.php	(working copy)
@@ -1907,11 +1907,10 @@
 		unset($this->comment_feed_structure);
 		$this->use_trailing_slashes = ( '/' == substr($this->permalink_structure, -1, 1) );
 
-		// Enable generic rules for pages if permalink structure doesn't begin with a wildcard.
-		if ( preg_match("/^[^%]*%(?:postname|category|tag|author)%/", $this->permalink_structure) )
-			 $this->use_verbose_page_rules = true;
-		else
-			$this->use_verbose_page_rules = false;
+		$clean_structure = str_replace( '/index.php', '', $this->permalink_structure );
+		if ( is_multisite() && !is_subdomain_install() && is_main_site() )
+			$clean_structure = str_replace( '/blog', '', $clean_structure );
+		$this->use_verbose_page_rules = (bool) preg_match( "#^/%(postname|category|tag|author)%#", $clean_structure );
 	}
 
 	/**