module dependencies issues

[Chris Angelico]

On Fri, Jul 10, 2015 at 7:33 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> And just how compatible does it have to be to get a tick?
>
> It must be a safe binary replacement of the earlier version. Bug fixes
> and new features are ok, but none of the old functionality can be
> obsoleted.

Your descriptions conflict. A safe binary replacement usually cannot
even add new features, in case this breaks something. Consider what
happens when Python creates a new keyword; it's a new feature, old
functionality hasn't been broken, but if that word had been used
anywhere as an identifier, it's now broken. Even something as simple
as updating to the latest Unicode release can change what means what,
and won't necessarily be backward-compatible (eg when a character's
classes are changed, the places where that character is legal may also
change). There is NO CHANGE which is perfectly backward-compatible.

ChrisA