this email have ever deliberately taken advantage of the limited Python 3 scope in comprehensions and generator expressions to use what would otherwise be a conflicting local variable name?
No, never, but the opposite has bitten me in production code (as I related several months back, a class-level variable was being used on the lhs of a comprehension and that failed when it was run in Py3).
The caveat is that our code base is Py2+Py3, so we have the mindset that comprehension variables always leak.