git gh-fetch/gh-push utilities to pull and update PR branches

git-gh-fetch

#!/bin/bash
if [[ $# -ne 2 ]]; then
  echo "Usage: $0 REPO_NAME FORK:BRANCH"
  exit 1
fi
repo="$1"
user="${2%%:*}"
branch="${2#*:}"
shift 2
exec git fetch "https://github.com/$user/$repo.git" "$branch" "$@"

git-gh-push

#!/bin/bash
if [[ $# -ne 2 ]]; then
  echo "Usage: $0 REPO_NAME FORK:BRANCH"
  exit 1
fi
repo="$1"
user="${2%%:*}"
branch="${2#*:}"
shift 2
exec git push "git@github.com:$user/$repo.git" "HEAD:$branch" "$@"