ZF-10475: Useless information in session error message.

Description

{{Zend_Session_Exception::handleSessionStartError()}} and {{Zend_Session_Exception::handleSilentWriteClose()}} attach $errcontext to self::$sessionStartError but it contains an Array so the error message looks like this:

```

I think we can remove $errcontext from these error messages because it does not provide any useful information.

PHP Manual: [set_error_handler()

Comments

Attached diff to remove $errorcontext from string.

Fixed in r23364.