So would you have done the same if the truck was the first in line at the lights?
Actually, technically what you and the car ahead of you did is an infringe-able offense. Read the sign on the back of the truck, and it was indicting to turn.
As a truck driver I would have very much appreciated having a vehicle stop behind me to block the lane needed for the truck to turn in. He was straddling the line markings in an attempt to encourage someone to do just that. You and the car in front of you just added to the stress of driving for that truckie. It's a hard enough job as it is.
I have talked to truck drivers who have ran over and crushed cars in situations like that.
So would you have done the same if the truck was the first in line at the lights?
Well there sure is conflicting info here.
Whilst what you say, that this road rule has been repealed :- http://www.austlii.edu.au/au/legis/nsw/repealed_reg/arr210/s143.html
Yet there is still this:- http://www.rms.nsw.gov.au/roads/safety-rules/road-rules/large-vehicles.html
where they make the distinction that if the truck is indicating to turn right you can't overtake it, yet doesn't mention the same for if the truck is indicating to turn left. Disappointing to see such ambiguity.