by a promise that the author plans to do it properly. The author
should however steadfastly resist pressure to put a timeframe to the
realization of that promise.
That's a good one ;)
It's a transitional thing, really. A more pukka way of doing this is to have an explicit pl.compat52 module, but that would be a breaking change.
I do feel however that creating a global setfenv is a mistake since it is often used as a marker for Lua 5.2. That might break a few things, but the cost is bearable.