clone: add --branch option to select a different HEAD

We currently point the HEAD of a newly cloned repo to the
same ref as the parent repo's HEAD. While a user can then
"git checkout -b foo origin/foo" whichever branch they
choose, it is more convenient and more efficient to tell
clone which branch you want in the first place.

Based on a patch by Kirill A. Korinskiy.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 68 insertions, 0 deletions

diff --git a/t/t5706-clone-branch.sh b/t/t5706-clone-branch.sh
new file mode 100755
index 0000000000..f3f9a76056
--- /dev/null
+++ b/t/t5706-clone-branch.sh
@@ -0,0 +1,68 @@
+#!/bin/sh
+
+test_description='clone --branch option'
+. ./test-lib.sh
+
+check_HEAD() {
+	echo refs/heads/"$1" >expect &&
+	git symbolic-ref HEAD >actual &&
+	test_cmp expect actual
+}
+
+check_file() {
+	echo "$1" >expect &&
+	test_cmp expect file
+}
+
+test_expect_success 'setup' '
+	mkdir parent &&
+	(cd parent && git init &&
+	 echo one >file && git add file && git commit -m one &&
+	 git checkout -b two &&
+	 echo two >file && git add file && git commit -m two &&
+	 git checkout master)
+'
+
+test_expect_success 'vanilla clone chooses HEAD' '
+	git clone parent clone &&
+	(cd clone &&
+	 check_HEAD master &&
+	 check_file one
+	)
+'
+
+test_expect_success 'clone -b chooses specified branch' '
+	git clone -b two parent clone-two &&
+	(cd clone-two &&
+	 check_HEAD two &&
+	 check_file two
+	)
+'
+
+test_expect_success 'clone -b sets up tracking' '
+	(cd clone-two &&
+	 echo origin >expect &&
+	 git config branch.two.remote >actual &&
+	 echo refs/heads/two >>expect &&
+	 git config branch.two.merge >>actual &&
+	 test_cmp expect actual
+	)
+'
+
+test_expect_success 'clone -b does not munge remotes/origin/HEAD' '
+	(cd clone-two &&
+	 echo refs/remotes/origin/master >expect &&
+	 git symbolic-ref refs/remotes/origin/HEAD >actual &&
+	 test_cmp expect actual
+	)
+'
+
+test_expect_success 'clone -b with bogus branch chooses HEAD' '
+	git clone -b bogus parent clone-bogus &&
+	(cd clone-bogus &&
+	 check_HEAD master &&
+	 check_file one
+	)
+'
+
+test_done