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

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

third_party/git/t/t3513-revert-submodule.sh

@@ -0,0 +1,31 @@
+#!/bin/sh
+
+test_description='revert can handle submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+# Create a revert that moves from HEAD (including any test modifications to
+# the work tree) to $1 by first checking out $1 and reverting it. Reverting
+# the revert is the transition we test for. We tar the current work tree
+# first so we can restore the work tree test setup after doing the checkout
+# and revert.  We test here that the restored work tree content is identical
+# to that at the beginning. The last revert is then tested by the framework.
+git_revert () {
+	git status -su >expect &&
+	ls -1pR * >>expect &&
+	tar cf "$TRASH_DIRECTORY/tmp.tar" * &&
+	git checkout "$1" &&
+	git revert HEAD &&
+	rm -rf * &&
+	tar xf "$TRASH_DIRECTORY/tmp.tar" &&
+	git status -su >actual &&
+	ls -1pR * >>actual &&
+	test_cmp expect actual &&
+	git revert HEAD
+}
+
+KNOWN_FAILURE_NOFF_MERGE_DOESNT_CREATE_EMPTY_SUBMODULE_DIR=1
+test_submodule_switch "git_revert"
+
+test_done