[PATCH] contrib/subtree bugfix: Can't `add` annotated 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(-)