Git show branches into which the current branch has been merged into.

git-show-merged

#!/usr/bin/env ruby

# git-show-merged: a simple script to show you which topic branches the
# current branch has been merged into, and which it hasn't.
#
# git-show-merged Copyright 2010 Birkir A. Barkarson <birkirb@stoicviking.net>. 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or (at
# your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You can find the GNU General Public License at:
#   http://www.gnu.org/licenses/
heads = if ARGV.empty?
  [`git symbolic-ref HEAD`.chomp]
else
  ARGV
end.map { |r| r.gsub(/refs\/heads\//, "") }

head = heads.first
branches = `git show-ref --heads`.scan(/^\S+ refs\/heads\/(\S+)$/).map { |a| a.first }

branches -= heads
if branches.empty?
  $stderr.puts "No branches!"
  exit(-1)
end

merged = Array.new

branches.each do |b|
  `git checkout #{b} 2>&1`
  if "" == `git log #{b}..#{head}`
    merged << b
  end
end

`git checkout #{head} 2>&1`

not_merged = branches - merged

puts "#{head} is merged into:"
merged.each { |b| puts "  #{b}" }
puts
puts "#{head} is not merged into:"
not_merged.each { |b| puts "  #{b}" }
puts