Debian Python Policy
Chapter 1 - On the move to Python 3
Debian currently supports two Python stacks, one for Python 2 and one for
Python 3. The long term goal for Debian is to reduce this to one stack,
dropping the Python 2 stack at some time. PEP 404 states
that no more major Python 2 releases are planned, although the last released
major version 2.7 will see some extended support, documented in PEP 466.
Packages in Debian should use Python 3 if Python 3 is supported. New packages
should use Python 3 from the initial upload, new upstream versions for existing
packages should use Python 3 if the new upstream version supports it.
Programs should use Python 3, and should not be packaged for Python 2 as well.
Python 3 should be used for the packaging if the packaging scripts use Python.
Python libraries should be always packaged for Python 3 if supported. Python 2
libraries should be packaged, if applications found in the reverse dependencies
are not yet supported by Python 3.
Existing Python 2 libraries should not be dropped before the last reverse
dependency is removed.