hhvm&nginx duplicate response headers

[disem]

While using debug module with hhvm & nginx i'm getting duplicate response headers

Cache-Control:no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Cache-Control:no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Expires:Thu, 19 Nov 1981 08:52:00 GMT
Expires:Thu, 19 Nov 1981 08:52:00 GMT
Pragma:no-cache
Pragma:no-cache

The reason is RequestPanel which executes Yii::$app->get('session') for logging flash messages.
I'm not sure where is the actual reason for such behavior but after commenting out 'flashes' => $this->getFlashes(), from the save()'s return statement - headers has no duplicates.

[cebe]

thats really weird, these headers are not set by yii itself so I think it is necessary to reprocuce it with plain php and report to HHVM...

[disem]

Got some time to take a closer look at this issue. The reason is multiple session_start() call. Reported to HHVM facebook/hhvm/issues/5437