gh pr push <pr_number>

.zshrc

# Pushes to the remote that the PR was created from
# Useful for open source projects that allows maintainers to edit
# Requires "brew install jq"
# Requires "brew install github/gh/gh"
function pr_push {
  ORG_AND_REPO=$(git remote get-url origin | sed 's/.*\/\([^ ]*\/[^.]*\).*/\1/')

  REMOTE_URL=$(curl https://api.github.com/repos/$ORG_AND_REPO/pulls/${1:?"The PR number must be specified"} | jq .head.repo.clone_url | tr -d '"')
  BRANCH=$(git rev-parse --abbrev-ref HEAD)

  echo "Going to execute: git push $REMOTE_URL $BRANCH"

  $(git push $REMOTE_URL $BRANCH)
}

# Push equivalent of https://cli.github.com/manual/gh_pr_checkout
# gh pr push <pr_number>
gh() {
  if [ "$1" = "pr" ] && [ "$2" = "push" ]; then
    pr_push $3
  else
    command gh "$@"
  fi
}