The GitHub "command line instructions" for PR merging assume you'll be merging and pushing changes from the command line rather than amending the original PR. This means I'm not entirely clear on how to amend the following prior to accepting someone's change:

• update ACKs
• add a NEWS entry
• add a What's New entry
• any other tweaks I want to just fix myself rather than pushing back for another round of review

https://help.github.com/articles/committing-changes-to-a-pull-request-branch-created-from-a-fork/ seems to be the main documentation for this, but making a full clone for this purpose seems a little excessive given the size of the CPython repository.

I'm going to try using a shallow clone for the purpose: https://www.perforce.com/blog/141218/git-beyond-basics-using-shallow-clones