Re: [PATCH] git-bisect.sh: don't accidentally override existing branch "bisect"

> If a branch named "bisect" or "new-bisect" already was created in the
> repo by other means than git bisect, doing a git bisect used to override
> the branch without a warning.  Now if the branch "bisect" or
> "new-bisect" already exists, and it was not created by git bisect itself,
> git bisect start fails with an appropriate error message.  Additionally,
> if checking out a new bisect state fails due to a merge problem, git
> bisect cleans up the temporary branch "new-bisect".
>
> The accidental override has been noticed by Andres Salomon, reported
> through
>  http://bugs.debian.org/478647
>
> Signed-off-by: Gerrit Pape <pape@smarden.org>
> ---
>  Documentation/git-bisect.txt |    2 +-
>  git-bisect.sh                |   20 ++++++++++++++------
>  t/t6030-bisect-porcelain.sh  |   18 ++++++++++++++++++
>  3 files changed, 33 insertions(+), 7 deletions(-)
>
> diff --git a/Documentation/git-bisect.txt b/Documentation/git-bisect.txt
> index 698ffde..1c7e38d 100644
> --- a/Documentation/git-bisect.txt
> +++ b/Documentation/git-bisect.txt
> @@ -85,7 +85,7 @@ Oh, and then after you want to reset to the original
> head, do a $ git bisect reset
>  ------------------------------------------------
>
> -to get back to the master branch, instead of being in one of the
> +to get back to the original branch, instead of being in one of the
>  bisection branches ("git bisect start" will do that for you too,
>  actually: it will reset the bisection state, and before it does that
>  it checks that you're not using some old bisection branch).
> diff --git a/git-bisect.sh b/git-bisect.sh
> index d8d9bfd..48d81d5 100755
> --- a/git-bisect.sh
> +++ b/git-bisect.sh
> @@ -69,14 +69,19 @@ bisect_start() {
>  	head=$(GIT_DIR="$GIT_DIR" git symbolic-ref -q HEAD) ||
>  	head=$(GIT_DIR="$GIT_DIR" git rev-parse --verify HEAD) ||
>  	die "Bad HEAD - I need a HEAD"
> +	#
> +	# Check that we either already have BISECT_START, or that the
> +	# branches bisect, new-bisect don't exist, to not override them.
> +	#
> +	test -s "$GIT_DIR/BISECT_START" ||
> +		if git show-ref bisect > /dev/null ||
> +		    git show-ref new-bisect > /dev/null; then
> +			die 'The branches "bisect" and "new-bisect" must not exist.'
> +		fi

>  	start_head=''
>  	case "$head" in
>  	refs/heads/bisect)
> -		if [ -s "$GIT_DIR/BISECT_START" ]; then
> -		    branch=`cat "$GIT_DIR/BISECT_START"`
> -		else
> -		    branch=master
> -		fi
> +		branch=`cat "$GIT_DIR/BISECT_START"`
>  		git checkout $branch || exit
>  		;;
>  	refs/heads/*|$_x40)
> @@ -329,7 +334,10 @@ bisect_next() {
>
>  	echo "Bisecting: $bisect_nr revisions left to test after this"
>  	git branch -f new-bisect "$bisect_rev"
> -	git checkout -q new-bisect || exit
> +	git checkout -q new-bisect || {
> +		git branch -d new-bisect
> +		exit

> +	}
>  	git branch -M new-bisect bisect
>  	git show-branch "$bisect_rev"
>  }
> diff --git a/t/t6030-bisect-porcelain.sh b/t/t6030-bisect-porcelain.sh
> index 5e3e544..05f1e15 100755
> --- a/t/t6030-bisect-porcelain.sh
> +++ b/t/t6030-bisect-porcelain.sh
> @@ -284,6 +284,24 @@ test_expect_success 'bisect starting with a detached
> HEAD' '
>
>  '
>
> +test_expect_success 'bisect refuses to start if branch bisect exists' '
> +	git bisect reset &&
> +	git branch bisect &&
> +	test_must_fail git bisect start &&
> +	git branch -d bisect &&
> +	git checkout -b bisect &&
> +	test_must_fail git bisect start &&
> +	git checkout master &&
> +	git branch -d bisect
> +'
> +
> +test_expect_success 'bisect refuses to start if branch new-bisect
> exists' ' +	git bisect reset &&
> +	git branch new-bisect &&
> +	test_must_fail git bisect start &&
> +	git branch -d new-bisect
> +'
> +
>  #
>  #
>  test_done