Merging Bootstrap with squash merges to master

gistfile1.sh

# An approach of incorporating Bootstrap into a git repo,
# using subtree merging. This approach does squash merges
# from bootstrap-upstream to master, and results in merge
# conflicts.
#
# This gist is part of this StackOverflow question
# http://stackoverflow.com/questions/23095230/incorporating-bootstrap-into-a-git-repo-using-subtree-merging

# Create the repo
git init .
touch README.md
git add --all
git commit -am "Initial version"

# Add bootstrap as a remote
git remote add bootstrap https://github.com/twbs/bootstrap.git
# Only fetch the master branch; don't fetch tags
git config remote.bootstrap.fetch +refs/heads/master:refs/remotes/bootstrap/master
git config remote.bootstrap.tagopt --no-tags
git fetch bootstrap

# Make tags for the two bootstrap versions we need
git tag bootstrap-v3.1.0 1409cde7e800ca83fd761f87e5ad8f0d259e38d1
git tag bootstrap-v3.1.1 a365d8689c3f3cee7f1acf86b61270ecca8e106d
git checkout -b bootstrap-upstream bootstrap/master

# Start with Bootstrap v3.1.0
git checkout master
git read-tree -u --prefix=bootstrap/ bootstrap-v3.1.0
git commit -am "Bootstrap v3.1.0"

# Make some changes on master, so that we have something to
# be merged
sed -e 's/= space/= force-merge-conflict/g' -i '' bootstrap/.editorconfig
git commit -am "Force a merge conflict"
sed -e 's/"Helvetica Neue"/"Comic Sans"/g' -i '' bootstrap/less/variables.less 
git commit -am "Comic Sans"

# Merge Bootstrap v3.1.1 to master
git checkout master

# Doing a subtree merge does not work: The result is that most of the 
# bootstrap files are deleted. Perhaps it's related to this problem?
# http://stackoverflow.com/questions/1306595/git-confused-when-merging-an-update-into-my-subtree?rq=1
#
# git merge --squash -s subtree --no-commit bootstrap-v3.1.1

# Instead, pass in the subtree argument to recursive merge, which explicitly
# tells git where we put bootstrap.
#
# Note: "bootstrap" cannot end in a slash. See 
# http://git.661346.n2.nabble.com/Bug-Subtree-merge-seems-to-choke-on-trailing-slashes-td7570648.html
git merge --squash -s recursive -X subtree=bootstrap --no-commit bootstrap-v3.1.1


# The big problem happens here: We get over 100 merge conflicts in the Bootstrap code.
# Every file that changed in Bootstrap has a merge conflict.