I would say neither. We follow a single-commit rebase model, where any given "pull request" seeks to merge one commit on top of the main branch (master).
If the main line changes, then we git pull it to update the branch locally, and then git rebase the feature branch (with the single new commit), on it and then push again.
If new changes need to be made on the feature branch, then they are absorbed into the commit via git commit --amend in order to maintain that single commit workflow.