Masih, I think if you have a PhD from a reputed institution, nobody will ask about how long your Master's took. Anyway, statistics show that for academic success in Germany it is the total duration from starting at University to completion of PhD which is a good indicator, not the length of either part. If you take that job, which sounds great, then you have good hopes of finishing your PhD soon which is more important than a year more or less on your Master's.
Any 'blemish' on your CV would be well made up by the fact that you got a job at a reputed institution when you weren't even finished with your Master's.
I suppose you just need to consider carefully if you can do it considering the sudden move. If you can, I'd go for it! Or else you can trust some other, equally interesting opportunities will come up when you are more ready for them.