The problem with Python2.7 is that 'open' does not take 'closefd', or any of the other parameters that were added for Python3.

    open(name[, mode[, buffering]])

'rb' may make a difference on Py2 on Windows, but I haven't done any work in the environment in a long time.

I wasn't aware of that other issue.  Some core Python developers have participated in that one.  I suspect a lot of the discussion is beyond my level of expertise.

I once wrote that I thought 'FileType' was included primarily as an example of a 'type' factory.  Something users could copy and extend for their own use.  Bethard corrected me, saying that it was meant for quick-n-dirty script uses, ones with an input file, output file and a few options.  In a bigger scripts, the users are encouraged to open/close files in 'with' contexts.

See http://bugs.python.org/issue22884 and the issues I reference there.