ZF-8633: Locale corruption of Zend_Cache IDs
Zend_Cache_Core defines a method to validate IDs, stated to match the pattern [a-zA-Z0-9_]. In reality, the regular expression used is [\w]+. While ordinarily this is correct, on a system where PECL has been compiled with additional locales, the \w "word" will match additional locale specific characters. In order to avoid this, the regular expression used should be made explicit to avoid such additional character matches.