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/t3906-stash-submodule.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-test_description='stash can handle submodules'
+test_description='stash apply can handle submodules'
 
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-submodule-update.sh
@@ -21,44 +21,4 @@ KNOWN_FAILURE_CHERRY_PICK_SEES_EMPTY_COMMIT=1
 KNOWN_FAILURE_NOFF_MERGE_DOESNT_CREATE_EMPTY_SUBMODULE_DIR=1
 test_submodule_switch "git_stash"
 
-setup_basic () {
-	test_when_finished "rm -rf main sub" &&
-	git init sub &&
-	(
-		cd sub &&
-		test_commit sub_file
-	) &&
-	git init main &&
-	(
-		cd main &&
-		git submodule add ../sub &&
-		test_commit main_file
-	)
-}
-
-test_expect_success 'stash push with submodule.recurse=true preserves dirty submodule worktree' '
-	setup_basic &&
-	(
-		cd main &&
-		git config submodule.recurse true &&
-		echo "x" >main_file.t &&
-		echo "y" >sub/sub_file.t &&
-		git stash push &&
-		test_must_fail git -C sub diff --quiet
-	)
-'
-
-test_expect_success 'stash push and pop with submodule.recurse=true preserves dirty submodule worktree' '
-	setup_basic &&
-	(
-		cd main &&
-		git config submodule.recurse true &&
-		echo "x" >main_file.t &&
-		echo "y" >sub/sub_file.t &&
-		git stash push &&
-		git stash pop &&
-		test_must_fail git -C sub diff --quiet
-	)
-'
-
 test_done