merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/t/t4255-am-submodule.sh

@@ -0,0 +1,93 @@
+#!/bin/sh
+
+test_description='git am handling submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+am () {
+	git format-patch --stdout --ignore-submodules=dirty "..$1" | git am -
+}
+
+test_submodule_switch "am"
+
+am_3way () {
+	git format-patch --stdout --ignore-submodules=dirty "..$1" | git am --3way -
+}
+
+KNOWN_FAILURE_NOFF_MERGE_ATTEMPTS_TO_MERGE_REMOVED_SUBMODULE_FILES=1
+test_submodule_switch "am_3way"
+
+test_expect_success 'setup diff.submodule' '
+	test_commit one &&
+	INITIAL=$(git rev-parse HEAD) &&
+
+	git init submodule &&
+	(
+		cd submodule &&
+		test_commit two &&
+		git rev-parse HEAD >../initial-submodule
+	) &&
+	git submodule add ./submodule &&
+	git commit -m first &&
+
+	(
+		cd submodule &&
+		test_commit three &&
+		git rev-parse HEAD >../first-submodule
+	) &&
+	git add submodule &&
+	git commit -m second &&
+	SECOND=$(git rev-parse HEAD) &&
+
+	(
+		cd submodule &&
+		git mv two.t four.t &&
+		git commit -m "second submodule" &&
+		git rev-parse HEAD >../second-submodule
+	) &&
+	test_commit four &&
+	git add submodule &&
+	git commit --amend --no-edit &&
+	THIRD=$(git rev-parse HEAD) &&
+	git submodule update --init
+'
+
+run_test() {
+	START_COMMIT=$1 &&
+	EXPECT=$2 &&
+	# Abort any merges in progress: the previous
+	# test may have failed, and we should clean up.
+	test_might_fail git am --abort &&
+	git reset --hard $START_COMMIT &&
+	rm -f *.patch &&
+	git format-patch -1 &&
+	git reset --hard $START_COMMIT^ &&
+	git submodule update &&
+	git am *.patch &&
+	git submodule update &&
+	git -C submodule rev-parse HEAD >actual &&
+	test_cmp $EXPECT actual
+}
+
+test_expect_success 'diff.submodule unset' '
+	test_unconfig diff.submodule &&
+	run_test $SECOND first-submodule
+'
+
+test_expect_success 'diff.submodule unset with extra file' '
+	test_unconfig diff.submodule &&
+	run_test $THIRD second-submodule
+'
+
+test_expect_success 'diff.submodule=log' '
+	test_config diff.submodule log &&
+	run_test $SECOND first-submodule
+'
+
+test_expect_success 'diff.submodule=log with extra file' '
+	test_config diff.submodule log &&
+	run_test $THIRD second-submodule
+'
+
+test_done