How on earth do I update this subtree? about mcudude_corefiles HOT 6 CLOSED

# create a working branch just to avoid messing up master if something goes wrong
git checkout -b update-core-subtree master
# create a remote for the core repository and fetch from it
git remote add -f MCUdude_corefiles-remote https://github.com/MCUdude/MCUdude_corefiles.git
# create a branch with the contents of the core repository's master branch
git branch MCUdude_corefiles-branch MCUdude_corefiles-remote/master
# update the core subtree
git merge --squash -s recursive -Xsubtree=avr/cores/MCUdude_corefiles -Xtheirs --allow-unrelated-histories --no-commit MCUdude_corefiles-branch
# commit the updates to the subtree
git commit -m 'Update core subtree to 3aa8d81' -m 'Fix tone() for ATmega64/128' -m 'https://github.com/MCUdude/MCUdude_corefiles/tree/3aa8d810b24952efc870483dfa2af609a50aa720'
git checkout master
# rebase the commit from the working branch to master
git rebase update-core-subtree
# delete the working branch
git branch -d update-core-subtree
# push the commit to GitHub
git push

# create a working branch just to avoid messing up master if something goes wrong
git checkout -b update-core-subtree master
# create a remote for the core repository and fetch from it
git remote add -f MCUdude_corefiles-remote https://github.com/MCUdude/MCUdude_corefiles.git
# create a branch with the contents of the core repository's master branch
git branch MCUdude_corefiles-branch MCUdude_corefiles-remote/master
# update the core subtree
git merge --squash -s subtree --allow-unrelated-histories --no-commit MCUdude_corefiles-branch
# commit the updates to the subtree
git commit -m 'Update core subtree to {latest commit short hash}' -m '{summary of changes since last update}' -m 'https://github.com/MCUdude/MCUdude_corefiles/tree/{latest commit hash}'
git checkout master
# rebase the commit from the working branch to master
git rebase update-core-subtree
# delete the working branch
git branch -d update-core-subtree
# push the commit to GitHub
git push

# create a working branch just to avoid messing up master if something goes wrong
git checkout -b update-core-subtree master
# create a remote for the core repository and fetch from it
git remote add -f MCUdude_corefiles-remote https://github.com/MCUdude/MCUdude_corefiles.git
# create a branch with the contents of the core repository's master branch
git branch MCUdude_corefiles-branch MCUdude_corefiles-remote/master
# update the core subtree
git merge --squash -s subtree -Xsubtree=avr/cores/MCUdude_corefiles --allow-unrelated-histories -m 'Update core subtree to 3aa8d81' -m 'Fix tone() for ATmega64/128' -m 'https://github.com/MCUdude/MCUdude_corefiles/tree/3aa8d810b24952efc870483dfa2af609a50aa720' MCUdude_corefiles-branch
# the above fails with "Automatic merge failed; fix conflicts and then commit the result."
# I had to fix the merge conflicts in README.md and Tone.cpp
# add the edits that fix the merge conflicts
git add .
# finally commit the updates to the subtree
git commit -m 'Update core subtree to 3aa8d81' -m 'Fix tone() for ATmega64/128' -m 'https://github.com/MCUdude/MCUdude_corefiles/tree/3aa8d810b24952efc870483dfa2af609a50aa720'
git checkout master
# rebase the commit from the working branch to master
git rebase update-core-subtree

$ git checkout -b update-core-subtree master
Switched to a new branch 'update-core-subtree'

$ git remote add -f MCUdude_corefiles-remote https://github.com/MCUdude/MCUdude_corefiles.git
fatal: remote MCUdude_corefiles-remote already exists.

$ git branch MCUdude_corefiles-branch MCUdude_corefiles-remote/master
Branch 'MCUdude_corefiles-branch' set up to track remote branch 'master' from 'MCUdude_corefiles-remote'.

$ git merge --squash -s subtree --allow-unrelated-histories --no-commit MCUdude_corefiles-branch
Squash commit -- not updating HEAD
Automatic merge went well; stopped before committing as requested

$ git commit -m "Update corefiles"
On branch update-core-subtree
nothing to commit, working tree clean

$ git checkout master
Switched to branch 'master'
Your branch is up to date with 'origin/master'.

$ git rebase update-core-subtree
Current branch master is up to date.

$ git branch -d update-core-subtree
Deleted branch update-core-subtree (was 972faf75).

$ git push
Everything up-to-date