lisp files in emacs git, emacs 24 compatible?

[Uwe Brauer]

Hello

Recently some Dmitry Gutov added some nice features to vc-hg.el

One way to use them is to downland and compile emacs git. But someone on
the mercurial mailing list asked me whether the new vc pkg or the
vc-hg.el is emacs  24 compatible.

This could be problematic

    -  vc-hg.el or all the vc files might include new lisp commands from
       other lisp files.

    -  they might contain even new command from C source code.

The question is:

    -  could changes in lisp packages be marked whether they are
       backward compatible say to GNU emacs 24?

    -  does it make sense to include them into  ELPA?

Regards

Uwe Brauer