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 #7919)
diff --git a/src/testdir/test_edit.vim b/src/testdir/test_edit.vim
index 6f083d9..0b44c7d 100644
--- a/src/testdir/test_edit.vim
+++ b/src/testdir/test_edit.vim
@@ -1704,6 +1704,7 @@
 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')
diff --git a/src/testdir/test_excmd.vim b/src/testdir/test_excmd.vim
index f27b385..0170a9f 100644
--- a/src/testdir/test_excmd.vim
+++ b/src/testdir/test_excmd.vim
@@ -333,6 +333,7 @@
 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:')
diff --git a/src/testdir/test_help.vim b/src/testdir/test_help.vim
index 219689b..966616c 100644
--- a/src/testdir/test_help.vim
+++ b/src/testdir/test_help.vim
@@ -74,6 +74,7 @@
 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')
 
diff --git a/src/testdir/test_writefile.vim b/src/testdir/test_writefile.vim
index 07beb64..e7a309a 100644
--- a/src/testdir/test_writefile.vim
+++ b/src/testdir/test_writefile.vim
@@ -406,6 +406,7 @@
 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
diff --git a/src/version.c b/src/version.c
index ffedb4f..add4c38 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2570,
+/**/
     2569,
 /**/
     2568,