Do you have a package that can be tested with? As far as I'm aware, the core system has never su

Ugh, fat finger on mobile, sorry.

... never supported this style XML which would mean you have to process this in an install script. With some tweaking in the JInstaller library, it is suggested to not use the singleton JInstaller::getInstance to fetch an instance because of object caching. Maybe you're hitting this issue?

You right, i have some process in install script.
But for each library use new object $install = new JInstaller.
So cache cant be set there as i understand.
In bottom exmple function with install libraries
private function installLibraries($parent)
{
// Required objects
$installer = new JInstaller;
$manifest = $parent->get('manifest');
$src = $parent->getParent()->getPath('source');

    if ($nodes = $manifest->libraries->library)
    {
        foreach ($nodes as $node)
        {
            $extName = $node->attributes()->name;
            $extPath = $src . '/libraries/' . $extName;
            $result  = 0;

            if (is_dir($extPath))
            {
                $result = $installer->install($extPath);
            }

            $this->_storeStatus('libraries', array('name' => $extName, 'result' => $result));
        }
    }
}<hr /><sub>This comment was created with the <a href="https://github.com/joomla/jissues">J!Tracker Application</a> at <a href="http://issues.joomla.org/tracker/joomla-cms/5909">issues.joomla.org/joomla-cms/5909</a>.</sub>

Guys thank you for help, i find a cache. Realy i use singleton. Need move $installer = new JInstaller; in foreach.
Issue can be closed.

Set to "closed" on behalf of @zero-24 by The JTracker Application at issues.joomla.org/joomla-cms/5909

Closing as requested thanks for the update