The current discrepancy is odd when you compare it to the equivalent generator expression:

    {k:v for k, v in iterable}

    dict(((k, v) for k, v in iterable))

It would never have occurred to me to expect the evaluation order to match a fully unrolled loop with a nested "d[k] = v" assignment, because the dict constructor doesn't work that way - it accepts an iterable of 2-tuples.

PEP 274 also specifies the iterable-of-2-tuples interpretation (using a list comprehension as its baseline rather than a generator expression): https://www.python.org/dev/peps/pep-0274/#semantics