cherry-pick: add t3512 for submodule updates

Test that the cherry-pick command updates the work tree as expected (for
submodule changes which don't result in conflicts).

Set KNOWN_FAILURE_NOFF_MERGE_ATTEMPTS_TO_MERGE_REMOVED_SUBMODULE_FILES
and KNOWN_FAILURE_NOFF_MERGE_DOESNT_CREATE_EMPTY_SUBMODULE_DIR to
document that cherry-pick has the same --no-ff known failures merge has.

Implement the KNOWN_FAILURE_CHERRY_PICK_SEES_EMPTY_COMMIT switch to expect
the known failure that while cherry picking just a SHA-1 update for an
ignored submodule the commit incorrectly fails with "The previous
cherry-pick is now empty, possibly due to conflict resolution.".

Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/lib-submodule-update.sh

@@ -402,7 +402,16 @@ test_submodule_switch () {
 
 	########################## Modified submodule #########################
 	# Updating a submodule sha1 doesn't update the submodule's work tree
-	test_expect_success "$command: modified submodule does not update submodule work tree" '
+	if test "$KNOWN_FAILURE_CHERRY_PICK_SEES_EMPTY_COMMIT" = 1
+	then
+		# When cherry picking a SHA-1 update for an ignored submodule
+		# the commit incorrectly fails with "The previous cherry-pick
+		# is now empty, possibly due to conflict resolution."
+		RESULT="failure"
+	else
+		RESULT="success"
+	fi
+	test_expect_$RESULT "$command: modified submodule does not update submodule work tree" '
 		prolog &&
 		reset_work_tree_to add_sub1 &&
 		(
@@ -418,7 +427,7 @@ test_submodule_switch () {
 
 	# Updating a submodule to an invalid sha1 doesn't update the
 	# submodule's work tree, subsequent update will fail
-	test_expect_success "$command: modified submodule does not update submodule work tree to invalid commit" '
+	test_expect_$RESULT "$command: modified submodule does not update submodule work tree to invalid commit" '
 		prolog &&
 		reset_work_tree_to add_sub1 &&
 		(
@@ -433,7 +442,7 @@ test_submodule_switch () {
 	'
 	# Updating a submodule from an invalid sha1 doesn't update the
 	# submodule's work tree, subsequent update will succeed
-	test_expect_success "$command: modified submodule does not update submodule work tree from invalid commit" '
+	test_expect_$RESULT "$command: modified submodule does not update submodule work tree from invalid commit" '
 		prolog &&
 		reset_work_tree_to invalid_sub1 &&
 		(

t/t3512-cherry-pick-submodule.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+test_description='cherry-pick can handle submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+KNOWN_FAILURE_CHERRY_PICK_SEES_EMPTY_COMMIT=1
+KNOWN_FAILURE_NOFF_MERGE_DOESNT_CREATE_EMPTY_SUBMODULE_DIR=1
+KNOWN_FAILURE_NOFF_MERGE_ATTEMPTS_TO_MERGE_REMOVED_SUBMODULE_FILES=1
+test_submodule_switch "git cherry-pick"
+
+test_done