Issue #306 - A sanity check within api_str_ireplace() has been added.

main/inc/lib/multibyte_string_functions.lib.php

@@ -586,6 +586,7 @@ function api_str_ireplace($search, $replace, $subject, & $count = null, $encodin
 	if (empty($encoding)) {
 		$encoding = _api_mb_internal_encoding();
 	}
+	if (api_is_encoding_supported($encoding)) {
 		if (!is_array($search) && !is_array($replace)) {
 			if (!api_is_utf8($encoding)) {
 				$search = api_utf8_encode($search, $encoding);
@@ -632,6 +633,11 @@ function api_str_ireplace($search, $replace, $subject, & $count = null, $encodin
 			}
 			return $subject;
 		}
+	}
+	if (is_null($count)) {
+		return str_ireplace($search, $replace, $subject);
+	}
+	return str_ireplace($search, $replace, $subject, $count);
 }
 
 /**