After the whole thing with the Gathering Bug, they seem to have fixed the stamina bar in such a way, that you can abuse it.
While doing the Manyu Daily i was "lucky" enough to get 4 wooden chests. Before finishing the mission i thought if it would be possible to restart the mission, so i terminated the Firefox Process in the task manager.

To my surprised it worked. It seems the Stamina only gets used, when you finish a mission, originally it was used when you started it. This can be potetially be used to reroll the outcome of a mission.

I give a small warning out, that it might not work for other people. I myself only tried it 2 times, with success, but still.
Would be interesting to know, if other people also tried it and if it worked or not.