checkout: allow dwim for branch creation for "git checkout $branch --"

The "--" notation disambiguates files and branches, but as a side-effect
of the previous implementation, also disabled the branch auto-creation
when $branch does not exist.

A possible scenario is then:

git checkout $branch
=> fails if $branch is both a ref and a file, and suggests --

git checkout $branch --
=> refuses to create the $branch

This patch allows the second form to create $branch, and since the -- is
provided, it does not look for file named $branch.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/t/t2024-checkout-dwim.sh b/t/t2024-checkout-dwim.sh
index dee55e428f..36be80fd41 100755
--- a/t/t2024-checkout-dwim.sh
+++ b/t/t2024-checkout-dwim.sh
@@ -164,4 +164,25 @@ test_expect_success 'checkout of branch from a single remote succeeds #4' '
 	test_branch_upstream eggs repo_d eggs
 '
 
+test_expect_success 'checkout of branch with a file having the same name fails' '
+	git checkout -B master &&
+	test_might_fail git branch -D spam &&
+
+	>spam &&
+	test_must_fail git checkout spam &&
+	test_must_fail git rev-parse --verify refs/heads/spam &&
+	test_branch master
+'
+
+test_expect_success 'checkout <branch> -- succeeds, even if a file with the same name exists' '
+	git checkout -B master &&
+	test_might_fail git branch -D spam &&
+
+	>spam &&
+	git checkout spam -- &&
+	test_branch spam &&
+	test_cmp_rev refs/remotes/extra_dir/repo_c/extra_dir/spam HEAD &&
+	test_branch_upstream spam repo_c spam
+'
+
 test_done