[PATCH v2] git-clone: Add option --branch to override initial branch

["Tor Arne Vestbø" <torarnv@gmail.com>]

The options --branch and -b allow the user to override the initial
branch created and checked out by git-clone (normally this is the
active branch of the remote repository).

If the selected branch is not found the operation aborts.

Signed-off-by: Tor Arne Vestbø <torarnv@gmail.com>
---

Something like this?

Documentation/git-clone.txt |    5 +++++
 builtin-clone.c             |   32 ++++++++++++++++++++++++++++----
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/Documentation/git-clone.txt b/Documentation/git-clone.txt
index 95f08b9..e7feb4d 100644
--- a/Documentation/git-clone.txt
+++ b/Documentation/git-clone.txt
@@ -119,6 +119,11 @@ then the cloned repository will become corrupt.
 	Instead of using the remote name 'origin' to keep track
 	of the upstream repository, use <name> instead.
 
+--branch <name>::
+-b <name>::
+	Instead of using the remote repository's active branch as the
+	initial branch, use <name> instead.
+
 --upload-pack <upload-pack>::
 -u <upload-pack>::
 	When given, and the repository to clone from is accessed
diff --git a/builtin-clone.c b/builtin-clone.c
index c338910..5fc01ce 100644
--- a/builtin-clone.c
+++ b/builtin-clone.c
@@ -38,6 +38,7 @@ static int option_quiet, option_no_checkout, option_bare, option_mirror;
 static int option_local, option_no_hardlinks, option_shared;
 static char *option_template, *option_reference, *option_depth;
 static char *option_origin = NULL;
+static char *option_branch = NULL;
 static char *option_upload_pack = "git-upload-pack";
 static int option_verbose;
 
@@ -66,6 +67,8 @@ static struct option builtin_clone_options[] = {
 		   "path to git-upload-pack on the remote"),
 	OPT_STRING(0, "depth", &option_depth, "depth",
 		    "create a shallow clone of that depth"),
+	OPT_STRING('b', "branch", &option_branch, "branch",
+		    "initial remote branch to check out"),
 
 	OPT_END()
 };
@@ -372,7 +375,9 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	const char *repo_name, *repo, *work_tree, *git_dir;
 	char *path, *dir;
 	int dest_exists;
-	const struct ref *refs, *head_points_at, *remote_head, *mapped_refs;
+	const struct ref *refs, *mapped_refs;
+	const struct ref *remote_head = NULL;
+	const struct ref *head_points_at = NULL;
 	struct strbuf key = STRBUF_INIT, value = STRBUF_INIT;
 	struct strbuf branch_top = STRBUF_INIT, reflog_msg = STRBUF_INIT;
 	struct transport *transport = NULL;
@@ -545,12 +550,31 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 
 		mapped_refs = write_remote_refs(refs, &refspec, reflog_msg.buf);
 
-		head_points_at = locate_head(refs, mapped_refs, &remote_head);
+		if (option_branch) {
+		    const int offset = 11;
+		    const char *branch = option_branch;
+		    if (!prefixcmp(branch, "refs/heads/"))
+			branch += offset;
+
+		    const struct ref *r;
+		    for (r = mapped_refs; r; r = r->next) {
+			if (!strcmp(r->name + offset, branch)) {
+			    /* Override initial branch */
+			    head_points_at = r;
+			    remote_head = r;
+			    break;
+			}
+		    }
+
+		    if (!head_points_at)
+			die("remote has no branch named '%s'.", option_branch);
+
+		} else {
+		    head_points_at = locate_head(refs, mapped_refs, &remote_head);
+		}
 	}
 	else {
 		warning("You appear to have cloned an empty repository.");
-		head_points_at = NULL;
-		remote_head = NULL;
 		option_no_checkout = 1;
 		if (!option_bare)
 			install_branch_config("master", option_origin,
-- 
1.6.2.rc2.17.g2aa38