Easily track which branches need updating (http://stackoverflow.com/a/866353/965226)

gistfile1.txt

git for-each-ref 'refs/heads/*' | \
  while read rev type ref; do
    branch=$(expr "$ref" : 'refs/heads/\(.*\)' )
    revs=$(git rev-list $rev..master)
    if [ -n "$revs" ]; then
      echo $branch needs update
      git diff --summary --shortstat -M -C -C $rev master
    fi
  done