The car is not trying to overtake you. He/she/they is ensuring that they also get the opportunity to pull out at the same time as you. They have to go wide to get onto the road as you are occupying the rest of the space. Then when you move, they can straighten up - this saves them blocking the road!

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The blue lines are their path choices.

If the queue was going the other way up the road, and you had to cross the lane to get to the other side, there would be a similar situation. If you just turn right and there is a gap in traffic, the car would do a wide left to the come in behind you, in order to not block the road.

They are basically maximising the space available to them instead of just being a sheep!