[PATCH v1 2/2] checkout: fix regression in checkout -b on intitial checkout

[Ben Peart <peartben@gmail.com>]

From: Ben Peart <benpeart@microsoft.com>

When doing a 'checkout -b' do a full checkout including updating the working
tree when doing the initial checkout.  This fixes the regression in behavior
caused by fa655d8411 checkout: optimize "git checkout -b <new_branch>"

Signed-off-by: Ben Peart <benpeart@microsoft.com>
---
 builtin/checkout.c         | 6 ++++++
 t/t2018-checkout-branch.sh | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 6fadf412e8..af6b5c8336 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -517,6 +517,12 @@ static int skip_merge_working_tree(const struct checkout_opts *opts,
 	if (core_apply_sparse_checkout && !checkout_optimize_new_branch)
 		return 0;
 
+	/*
+	 * We must do the merge if this is the initial checkout
+	 */
+	if (is_cache_unborn())
+		return 0;
+
 	/*
 	 * We must do the merge if we are actually moving to a new commit.
 	 */
diff --git a/t/t2018-checkout-branch.sh b/t/t2018-checkout-branch.sh
index 35999b3adb..c438889b0c 100755
--- a/t/t2018-checkout-branch.sh
+++ b/t/t2018-checkout-branch.sh
@@ -206,7 +206,7 @@ test_expect_success 'checkout -b after clone --no-checkout does a checkout of HE
 	rev="$(git -C src rev-parse HEAD)" &&
 	git clone --no-checkout src dest &&
 	git -C dest checkout "$rev" -b branch &&
-	test_must_fail test -f dest/a
+	test -f dest/a
 '
 
 test_done
-- 
2.19.1.gvfs.1.16.g9d1374d