I will prepare a 3.5 patch for this.  There are not many instances other than those you found (but several times as many in tests).  I presume that most non-test instances were converted by the 2to3 fixer.

How about frozenset([...]) to frozenset({...})?  There are 4 occurrences of this. The semantic match between frozenset and {...} is better than with [...], but the visual gain in nearly nil.

I will leave the one idlelib instance in CodeContext for when I am editing the file anyway (for both 3.4 and 3.5), which should be soon.