I would like to suggest the following:
This is as we don't have individual Python 3 tags, such as python-3.6. But we do however have version tags for Python 2, such as python-2.7. These version tags however don't incorporate all Python 2 versions into them - what should a user that has Python 2.5 code tag their question as?
This is like the questions "Is it time for the [python] to become extinct?" and "Synonymization proposal for version-specific language tags". However I don't wish for all the Python version tags to be incorporated into the python tag. It is only the Python 2 versions into a Python 2 tag.
There are benefits for situations like "(Optionally) add Python sub tags to questions". When I tag a question as a Python 2 question, I always use python-2.7, as it's unlikely to be another Python 2 version. This should also help in cases where users forget that python-2.6 is a tag, such as in the answers and comments below the above question.
Under this answer in 2014, this question was asked and our second highest 2.7 answer said:
And so can we make the tag python-2.x?