Fixed typo.

format.c

@@ -200,7 +200,7 @@ d_char *sanitize(const char *content)
                 xs *s3 = xs_join(el, " ");
 
                 s2 = xs_fmt("<%s%s%s%s>",
-                    v[1] == '/' ? "/" : "", tag, xs_list_len(s3) ? " " : "", s3);
+                    v[1] == '/' ? "/" : "", tag, xs_list_len(el) ? " " : "", s3);
             }
             else {
                 /* bad tag: escape it */