[git] Squash current feature branch in-place (from the last fork point to the tip of current branch)

git-my-squash

#!/bin/bash

base=$1

if [ "$base" == "" ]; then
    echo "Please specify a base branch"
    echo "Usage: git squash <base branch>"
    echo ""
    echo "<base branch>: the branch where your current branch forked off (normally it's 'master')"
    exit 1
fi

# Get the tip of current branch.
tip=$(git rev-parse HEAD)
echo "Current tip: $tip"

# Get the best common ancestor of current branch and $base.
from=$(git merge-base $tip $base)
echo "Squash from: $from"

# Squash from $point to the tip of current branch.
git reset --soft $from
git commit

# Ensure there are no differences between the original tip and the squashed one.
new=$(git rev-parse HEAD)
echo "-----------------------------------------------"
echo "Making sure the squash is correct by comparing:"
echo "   original tip: $tip"
echo "   squashed tip: $new"
git diff --exit-code $new $tip
ret=$?
if [ $ret -eq 0 ]; then
    echo "Success!"
else
    echo "[ERROR] There are differences after the squash, rolling back..."
    git reset --hard ORIG_HEAD
    echo "Your squash has been rolled back."
fi
exit $ret

git-extras provided an 'git-squash' implementation, but it is using 'git merge --squash' which I don't like very much, I'd prefer a in-place solution with 'git reset --soft'.