Git list merged branches in one branch, but not on another

git-mdiff

#!/bin/bash

# Git command to compare which branches are merged into one branch but not
# present in another. Useful for comparing which branches have been merged
# into a release branch that are already on the mainline branch.
#
# Usage:
#
#   git mdiff origin/master origin/integration
#   
#   - Reveals a list of remote branches that are present on integration but
#     not on master.
#      
#
# See https://stackoverflow.com/questions/8071079 for a nice situational
# diagram to explain the typical use case. 
#
# The following command does not work as a git alias because it depends on
# Process Substitution <(..) and does not work with /bin/sh which is what
# git uses to process aliases.
#

comm -12 <(sort <(git branch -r --no-merged $1 )) <(sort <(git branch -r --merged $2))