[OE-core] moving OpenEmbedded-core to Python 3

[Alexander Kanavin]

Hello everyone,

we want to deprecate Python 2 in oe-core and set Python 3 as the 
default, preferred choice. What does this mean?

1) Introducing new Python 2 dependencies via new recipes or additional 
DEPENDS etc. in existing recipes will be discouraged: you'll have to 
provide a reason.

2) Bitbake itself is at the moment Python 2 only - which will be addressed.

3) OE-core recipes that are currently dependent on Python 2 will be 
moved to Python 3 whenever possible (e.g. when nothing in oe-core 
requires them to be built against python 2). This may break some of your 
code, so please do try any patchsets before they land in master (or 
stable release), and suggest alternatives.

4) Of course, there is a large mass of Python 2 code out there, which 
may never be ported to Python 3, so Python 2 will continue to be 
provided at least until it's no longer supported upstream (the current 
date is 2020).

I'll prepare an initial patchset for review, so please keep an eye on it.


Thanks,
Alex