revert(3p/git): Revert merge of git upstream at v2.26.2

This causes cgit to serve error pages, which is undesirable.

This reverts commit 5229c9b232, reversing
changes made to f2b211131f.

third_party/git/t/t7420-submodule-set-url.sh

@@ -1,55 +0,0 @@
-#!/bin/sh
-#
-# Copyright (c) 2019 Denton Liu
-#
-
-test_description='Test submodules set-url subcommand
-
-This test verifies that the set-url subcommand of git-submodule is working
-as expected.
-'
-
-TEST_NO_CREATE_REPO=1
-. ./test-lib.sh
-
-test_expect_success 'submodule config cache setup' '
-	mkdir submodule &&
-	(
-		cd submodule &&
-		git init &&
-		echo a >file &&
-		git add file &&
-		git commit -ma
-	) &&
-	mkdir super &&
-	(
-		cd super &&
-		git init &&
-		git submodule add ../submodule &&
-		git commit -m "add submodule"
-	)
-'
-
-test_expect_success 'test submodule set-url' '
-	# add a commit and move the submodule (change the url)
-	(
-		cd submodule &&
-		echo b >>file &&
-		git add file &&
-		git commit -mb
-	) &&
-	mv submodule newsubmodule &&
-
-	git -C newsubmodule show >expect &&
-	(
-		cd super &&
-		test_must_fail git submodule update --remote &&
-		git submodule set-url submodule ../newsubmodule &&
-		grep -F "url = ../newsubmodule" .gitmodules &&
-		git submodule update --remote
-	) &&
-	git -C super/submodule show >actual &&
-	test_cmp expect actual
-'
-
-test_done