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From: =?UTF-8?q?Nguy=E1=BB=85n=20Th=C3=A1i=20Ng=E1=BB=8Dc=20Duy?= 
	<pclouds@gmail.com>
Subject: [PATCH v4 09/10] clone: allow --branch to take a tag
Date: Fri, 13 Jan 2012 14:22:01 +0700
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Cc: Junio C Hamano <gitster@pobox.com>,
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Because a tag ref cannot be put to HEAD, HEAD will become detached.
This is consistent with "git checkout <tag>".

This is mostly useful in shallow clone, where it allows you to clone a
tag in addtion to branches.

Signed-off-by: Nguy=E1=BB=85n Th=C3=A1i Ng=E1=BB=8Dc Duy <pclouds@gmail=
=2Ecom>
---
 Documentation/git-clone.txt |    5 +++--
 builtin/clone.c             |   13 +++++++++++++
 t/t5601-clone.sh            |    9 +++++++++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-clone.txt b/Documentation/git-clone.txt
index 4b8b26b..db2b29c 100644
--- a/Documentation/git-clone.txt
+++ b/Documentation/git-clone.txt
@@ -146,8 +146,9 @@ objects from the source repository into a pack in t=
he cloned repository.
 -b <name>::
 	Instead of pointing the newly created HEAD to the branch pointed
 	to by the cloned repository's HEAD, point to `<name>` branch
-	instead. In a non-bare repository, this is the branch that will
-	be checked out.
+	instead. `--branch` can also take tags and treat them like
+	detached HEAD. In a non-bare repository, this is the branch
+	that will be checked out.
=20
 --upload-pack <upload-pack>::
 -u <upload-pack>::
diff --git a/builtin/clone.c b/builtin/clone.c
index 6a2886a..a3c8f78 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -471,6 +471,11 @@ static void update_head(const struct ref *our, con=
st struct ref *remote,
 			update_ref(msg, "HEAD", our->old_sha1, NULL, 0, DIE_ON_ERR);
 			install_branch_config(0, head, option_origin, our->name);
 		}
+	} else if (our) {
+		struct commit *c =3D lookup_commit_reference(our->old_sha1);
+		/* --branch specifies a non-branch (i.e. tags), detach HEAD */
+		update_ref(msg, "HEAD", c->object.sha1,
+			   NULL, REF_NODEREF, DIE_ON_ERR);
 	} else if (remote) {
 		/*
 		 * We know remote HEAD points to a non-branch, or
@@ -770,6 +775,14 @@ int cmd_clone(int argc, const char **argv, const c=
har *prefix)
 				find_ref_by_name(mapped_refs, head.buf);
 			strbuf_release(&head);
=20
+			if (!our_head_points_at) {
+				strbuf_addstr(&head, "refs/tags/");
+				strbuf_addstr(&head, option_branch);
+				our_head_points_at =3D
+					find_ref_by_name(mapped_refs, head.buf);
+				strbuf_release(&head);
+			}
+
 			if (!our_head_points_at)
 				die(_("Remote branch %s not found in "
 				      "upstream %s, using HEAD instead"),
diff --git a/t/t5601-clone.sh b/t/t5601-clone.sh
index e0b8db6..67869b4 100755
--- a/t/t5601-clone.sh
+++ b/t/t5601-clone.sh
@@ -271,4 +271,13 @@ test_expect_success 'clone from original with rela=
tive alternate' '
 	grep /src/\\.git/objects target-10/objects/info/alternates
 '
=20
+test_expect_success 'clone checking out a tag' '
+	git clone --branch=3Dsome-tag src dst.tag &&
+	GIT_DIR=3Dsrc/.git git rev-parse some-tag >expected &&
+	test_cmp expected dst.tag/.git/HEAD &&
+	GIT_DIR=3Ddst.tag/.git git config remote.origin.fetch >fetch.actual &=
&
+	echo "+refs/heads/*:refs/remotes/origin/*" >fetch.expected &&
+	test_cmp fetch.expected fetch.actual
+'
+
 test_done
--=20
1.7.3.1.256.g2539c.dirty