checkoutbranch forcebranch option not implemented

[driusan]

In git.CheckoutBranch, the branch option (-b) is implemented but forcebranch (-B) isn't.

Implementing it should just be a matter of checking if the refspec exists before creating the branch, and erroring out if ForceBranch isn't set, but calling UpdateRef if it is.

[sirnewton01]

@driusan do you think that this might get us closer to finishing #113?

[driusan]

Looks like it would help a little, but not make a huge difference:

$ git grep -e "git checkout -B" t*.sh | cut -f 1 -d ':' | uniq
t0090-cache-tree.sh
t1408-packed-refs.sh
t1430-bad-ref-name.sh
t2018-checkout-branch.sh
t2024-checkout-dwim.sh
t3033-merge-toplevel.sh
t3412-rebase-root.sh
t4038-diff-combined.sh
t4061-diff-indent.sh
t6010-merge-base.sh
t7505-prepare-commit-msg-hook.sh
t7517-per-repo-email.sh
t7800-difftool.sh

(there's only 2 in t2018 and a bunch inf t2024, but t2024 says it's tests for "checking out unborn branches" which isn't really a huge priority..)

[sirnewton01]

It seems that the -B (force branch) option was already working. I have a PR open to add in some checkout branch tests: #193

[sirnewton01]

Unless there is any objection I'm going to close this one as done.

[driusan]

Seems like it's working to me too:

➜  dgit git:(master) ✗ ./dgit checkout -b adsf
➜  dgit git:(adsf) ✗ ./dgit checkout -B adsf
➜  dgit git:(adsf) ✗ ./dgit checkout -b adsf
Branch adsf already exists.
➜  dgit git:(adsf) ✗ ./dgit checkout -b adsf23
➜  dgit git:(adsf23) ✗