panelload triggered twice on "back" action

[pragmaware]

The panelload event is triggered twice when back is pressed.
This happens in runTransition(), the first time it triggers from the from transition end callback and the second time it triggers from the to transition end callback.

[imaffett]

Feel free to submit a PR with the fix since you've traced through the issue.

[bugre]

Hi @pragmaware

I think it is in someway related to the issue #903 , so if/when you're going to work on a fix, maybe the info there can help and/or avoid other problems.

thanks