method was never documented and is new so this should not be scary. If you
were using $response->has_write_fh, change to ->_has_write_fh (but please consider
a different way to do what you are doing...)
+ - make predicate on $req->env private. Potentially breaking change, but this
+ method was never documented and is new so this should not be scary. If you
+ were using $request->has_env, change to ->_has_env (but please consider
+ a different way to do what you are doing...)
5.90049_006 - 2013-11-04