Re: Revert-style merge/Working tree-only checkout?

> Hello,
>
> I am somewhat new to Git and I keep running into having to accomplish
> a certain task and reading through the documentation I can't seem to
> find any way of doing this easily.
>
> The problem is when branches diverge and I want to sync a branch to
> another branch with full overwrite, but maintain history and maintain
> separate branches.
>
> For example, say there is a branch "master" and I create a branch "b1"
> from master at some point. After this, there are 5 commits
> (C1,C2,C3,C4,C5) to master and
> 17 commits to b1 (let's call them cb1, cb2, cb3, ..., cb17). Say I
> want to create an 18-th commit to "b1" that makes it identical to the
> C5 (current) state of master. Essentially a single commit wipe of
> changes cb1 -> cb17 as well as application of C1->C5. So far I have
> found one way of accomplishing this, but it is difficult, error prone,
> slow and I just plain don't like it. I feel like there should be an
> easier way.
>
> What I currently do:
>
> $ rm -rf *
> $ git checkout -f master
> $ tar -cvzf /tmp/master.tar.gz *
> $ git checkout b1
> $ rm -rf *
> $ tar -xvzf /tmp/master.tar.gz
> $ git add
> $ git commit -a
> $ git merge master
>
>
> I've considered doing something like the following
>
> $ git checkout b1
> $ git revert b1~17..b1
> $ git merge master
>
> but it also seems wrong, and requires me to count the submits by hand,
> which seems silly --> I'm not actually reverting anything. I don't
> know if this would even work.
>
>
> Any suggestions on how to accomplish this easier? Some sort of a
> force-checkout that affects working tree only but not the index?
>