Re: [PATCH] contrib/subtree bugfix: Crash if FETCH_HEAD is tag

>cmd_add_commit() is passed FETCH_HEAD by cmd_add_repository, which is
>then rev-parsed into an object ID. However, if the user is fetching a
>tag rather than a branch HEAD, such as by executing:
>
>$ git subtree add -P oldGit https://github.com/git/git.git tags/v1.8.0
>
>The object ID is a tag and is never peeled, and the git commit-tree
>call
>(line 561) slaps us in the face because it doesn't handle tag IDs.
>
>Because peeling a committish ID doesn't do anything if it's already a
>commit, fix by peeling[1] the object ID before assigning it to $rev, as
>per the patch.
>
>[*1*]: Via peel_committish(), from git:git-sh-setup.sh
>
>Reported-by: Kevin Cagle <kcagle@micron.com>
>Diagnosed-by: Junio C Hamano <gitster@pobox.com>
>Signed-off-by: James Denholm <nod.helm@gmail.com>
>---
>NB: This bug doesn't surface when using --squash, as $rev is reassigned
>to the squash commit via new_squash_commit before git commit-tree sees
>it (though for simplicity, new_squash_commit now also sees the peeled
>ID).
>
>Also doesn't surface when using "git subtree merge", as git merge can
>handle tag objects.
>
>On a side note, if merging a tag without --squash, git merge recognises
>that it's a tag and adds a note to the merge commit body. It may be
>worth mimicking this when using "subtree merge --squash" or
>"subtree add".
>
> contrib/subtree/git-subtree.sh | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/contrib/subtree/git-subtree.sh
>b/contrib/subtree/git-subtree.sh
>index dc59a91..9453dae 100755
>--- a/contrib/subtree/git-subtree.sh
>+++ b/contrib/subtree/git-subtree.sh
>@@ -538,7 +538,7 @@ cmd_add_commit()
> {
> 	revs=$(git rev-parse $default --revs-only "$@") || exit $?
> 	set -- $revs
>-	rev="$1"
>+	rev=$(peel_committish "$1")
> 	
> 	debug "Adding $dir as '$rev'..."
> 	git read-tree --prefix="$dir" $rev || exit $?