Tests for marks.

STARTTEST
:so small.vim
:" test that a deleted mark is restored after delete-undo-redo-undo
:/^\t/+1
:set nocp viminfo+=nviminfo
madduu
:let a = string(getpos("'a"))
:$put ='Mark after delete-undo-redo-undo: '.a
:/^\t/,$wq! test.out
ENDTEST

	textline A
	textline B
	textline C

Results: