Branch cleanup. Made this a private gist to begin with, but people keep asking me for a link to it. Horray for open source! (:

branch_cleanup.rb

#!/usr/bin/env ruby

puts "Starting..."

branches = `git branch --merged`.split("\n").map { |branch| branch.strip }

pattern = (ARGV.shift || `whoami`).strip
branches.select! { |branch| branch.match(pattern) }

count = branches.size
puts "Deleting #{count} branches..."

branches.each do |branch|
  if system("git branch -d #{branch}")

    # Check if there is a remote branch present
    if system("git branch -a | grep origin/#{branch}")
      system("git push origin :#{branch}")
    end

    count = count - 1
    puts "deleted. (#{count} left)"
  else
    abort "FAILED TO DELETE #{branch}"
  end
end

Maybe add
'git fetch && git remote prune origin` at line 4?