vim-patch:8.2.2570: tests fail when run as root

Problem:    Tests fail when run as root.
Solution:   Add a comment mentioning the expected failure. (issue vim/vim#7919)

f9a65505d1

Co-authored-by: Bram Moolenaar <Bram@vim.org>

src/nvim/testdir/test_edit.vim

@@ -1834,6 +1834,7 @@ func Test_edit_charconvert()
 endfunc
 
 " Test for editing a file without read permission
+" NOTE: if you run tests as root this will fail.  Don't run tests as root!
 func Test_edit_file_no_read_perm()
   CheckUnix
   call writefile(['one', 'two'], 'Xfile')

src/nvim/testdir/test_excmd.vim

@@ -476,6 +476,7 @@ func Test_winsize_cmd()
 endfunc
 
 " Test for the :redir command
+" NOTE: if you run tests as root this will fail.  Don't run tests as root!
 func Test_redir_cmd()
   call assert_fails('redir @@', 'E475:')
   call assert_fails('redir abc', 'E475:')

src/nvim/testdir/test_help.vim

@@ -98,6 +98,7 @@ func Test_help_completion()
 endfunc
 
 " Test for the :helptags command
+" NOTE: if you run tests as root this will fail.  Don't run tests as root!
 func Test_helptag_cmd()
   call mkdir('Xdir/a/doc', 'p')
 

src/nvim/testdir/test_writefile.vim

@@ -419,6 +419,7 @@ func Test_patchmode()
 endfunc
 
 " Test for writing to a file in a readonly directory
+" NOTE: if you run tests as root this will fail.  Don't run tests as root!
 func Test_write_readonly_dir()
   " On MS-Windows, modifying files in a read-only directory is allowed.
   CheckUnix