I'm skeptical that a backport is a useful thing. First, the handler is 
primarily meant for use with PEP 383, which means that it's all 
internal; few applications will ever need to use it explicitly.

Furthermore, applications/libraries that do use it most likely will have 
to support 2.6 and earlier, as well, so they aren't helped with the 
handler. My advise to such libraries is that they should include and 
register their own implementation of it, or else fall back to "strict" 
on 2.x (say).

In any case: this issue is closed by PEP 383 being implemented. If you 
still desire a backport, please create a new report.