I did something this morning while riding to work that I shall not be doing again in a similar situation. Seeing an oncoming car that had stopped momentarily to let someone out of a side road on his left, I stopped myself and nodded for him to come out as no oncoming traffic was in motion. Someone had to or he would never have gotten out. At that point, a car that had been waiting behind the car that had stopped, got bored with waiting, darted out and overtook him, narrowly missing the car that had just start to exit the side road. Felt a right idiot that I nearly caused an accident. Lesson learned and yes, I know… poor obs.
Curiously enough I was caught out by something almost the same when I was in West Germany. I was the one coming out of side road. Another driver needed to enter the side road but couldn't until I came out as it was too narrow. He waited, I came out and was hit by a car overtaking him. They don't have the caveat of not overtaking near junctions as we do here and I was the one deemed at fault.

