Zend Circular Dependency Issue

Question

I have a method within my bootstrap that sets up the caches for the application:

protected function _initSetCaches()
{
    $this->bootstrap(array('Db','CacheManager'));
    Zend_Db_Table_Abstract::setDefaultMetadataCache(Master::cache('database'));
    Zend_Translate::setCache(Master::cache());
    Zend_Date::setOptions(array('cache' => Master::cache()));
    Zend_Paginator::setCache(Master::cache());
    Zend_Locale::setCache(Master::cache());
    Zend_Locale_Data::setCache(Master::cache());
 }

As you can see, I set the various caches from calling a Master class containing a cache method. Within the cache method, I fetch the bootstrap object (self::bootstrap()) and then grab the cache type from the cachemanager resource. Here is the cache method within my Master class:

public static function cache($type='core')
{
    $registryKey = 'master_cache_' . $type;
    if(!self::registry($registryKey)){
        $manager = self::bootstrap()->getPluginResource('cachemanager')->getCacheManager();
        if(!$manager->hasCache($type)){
             self::throwException(sprintf("%s is not an available cache",$type));
        }
        $cache = $manager->getCache($type);
        self::register($registryKey,$cache);
     }
     return self::registry($registryKey);
}

As you can see, this method fetches the cachemanager from the bootstrap (self::bootstrap()). My issue is the following... If I implement my bootstrap method as follows (registering the bootstrap by fetching it through the application object (self::app()):

public static function bootstrap()
{
    if(!self::registry('master_bootstrap')){
        self::register('master_bootstrap', self::app()->getBootstrap());
    }
    return self::registry('master_bootstrap');
}

then everything works fine. However, this is a different implementation that what I originally had, which consequently, throws a circular dependancy exception. Here is my original implementation:

public static function bootstrap()
{
      return self::app()->getBootstrap();
}

Im confused as to why when I register the bootstrap within the global registry I can use the cache method, however, if I just return the bootstrap object directly, it results in a circular dependency issue. Shouldnt the implementation in which I register the bootstrap object in the global registry still cause a circular dependency?