Tasks inside ParallelFor receive the loop variable instead of other arguments

[Ark-kun]

One of our users has reported the following issue:

outside_task = op1()
items_gen_task = op2()

with dsl.ParallelFor(items_gen_task.outputs['Items']) as loop_item:
    inner_task = op3(param1=loop_item.a, param2=outside_task.outputs['Output'])

The issue is that op3 receives param2=loop_item.a instead of param2=outside_task.outputs['Output'].

[philippslang]

#2936