submodule--helper: teach push-check to handle HEAD

In 06bf4ad1d (push: propagate remote and refspec with
--recurse-submodules) push was taught how to propagate a refspec down to
submodules when the '--recurse-submodules' flag is given.  The only refspecs
that are allowed to be propagated are ones which name a ref which exists
in both the superproject and the submodule, with the caveat that 'HEAD'
was disallowed.

This patch teaches push-check (the submodule helper which determines if
a refspec can be propagated to a submodule) to permit propagating 'HEAD'
if and only if the superproject and the submodule both have the same
named branch checked out and the submodule is not in a detached head
state.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 24 insertions, 1 deletions

diff --git a/t/t5531-deep-submodule-push.sh b/t/t5531-deep-submodule-push.sh
index 57ba322..9e4410b 100755
--- a/t/t5531-deep-submodule-push.sh
+++ b/t/t5531-deep-submodule-push.sh
@@ -512,7 +512,8 @@ test_expect_success 'push propagating refspec to a submodule' '
 	# Fails when refspec includes an object id
 	test_must_fail git -C work push --recurse-submodules=on-demand origin \
 		"$(git -C work rev-parse branch2):refs/heads/branch2" &&
-	# Fails when refspec includes 'HEAD' as it is unsupported at this time
+	# Fails when refspec includes HEAD and parent and submodule do not
+	# have the same named branch checked out
 	test_must_fail git -C work push --recurse-submodules=on-demand origin \
 		HEAD:refs/heads/branch2 &&
 
@@ -527,4 +528,26 @@ test_expect_success 'push propagating refspec to a submodule' '
 	test_cmp expected_pub actual_pub
 '
 
+test_expect_success 'push propagating HEAD refspec to a submodule' '
+	git -C work/gar/bage checkout branch2 &&
+	> work/gar/bage/junk12 &&
+	git -C work/gar/bage add junk12 &&
+	git -C work/gar/bage commit -m "Twelfth junk" &&
+
+	git -C work checkout branch2 &&
+	git -C work add gar/bage &&
+	git -C work commit -m "updating gar/bage in branch2" &&
+
+	# Passes since the superproject and submodules HEAD are both on branch2
+	git -C work push --recurse-submodules=on-demand origin \
+		HEAD:refs/heads/branch2 &&
+
+	git -C submodule.git rev-parse branch2 >actual_submodule &&
+	git -C pub.git rev-parse branch2 >actual_pub &&
+	git -C work/gar/bage rev-parse branch2 >expected_submodule &&
+	git -C work rev-parse branch2 >expected_pub &&
+	test_cmp expected_submodule actual_submodule &&
+	test_cmp expected_pub actual_pub
+'
+
 test_done