Is the Last Raka at His First or Is It His Last?

If the person caught one raka then he takes the hukum of the moon and as the moon he cannot become the imam of somebody else. In this case really the best thing to do is not have a second jamara anyway much less tap somebody and then start another jamara. There's two versions of the hadith right what my fakdu for attim mu you complete what's remaining  and there's an issue of whether or not some brothers stand from the third raka when they pray.