Re: Duplicating a branch

[Junio C Hamano <gitster@pobox.com>]

"Aaron Gray" <aaronngray.lists@googlemail.com> writes:

> How do I go about duplicating a branch within a repository, so I can
> make test mods ?

Run

    $ git checkout -b experiment master

to make a new "experiment" branch that points at the same comit as
"master" (or whatever other branch), hack away (including committing which
would grow the history of "experiment" branch without touching "master").

After you are done, and if you want to discard it, simply:

    $ git checkout master
    $ git branch -D experiment

or if you want to keep all of it:

    $ git checkout master
    $ git merge experiment

*BUT* if your "experiment" was truly exploratory in the sense that your
history is full of "let's try this, commit to snapshot, test, oops, it did
not work, let's try that, commit to snapshot, test, ok, I made some
progress, let's continue" crufts, you would most likely want to clean-up
your history before the latter "checkout master and merge experiment into
it" steps with something like:

    $ git rebase -i master experiment

If you in advance know that what you are going to do is truly "throw-away
experiment", you do not even need to use an "experiment" branch.  You can
do your exploration while on a detached HEAD:

    $ git checkout master^0

and hack away, including making commits (but you will discard them in
the end), and then finally:

    $ git reset --hard ;# if you have local changes you do not want to
			  take back to master
    $ git checkout master