patch 9.0.0464: with virtual text "above" indenting doesn't work well

Problem:    With virtual text "above" indenting doesn't work well.
Solution:   Ignore text properties while adjusting indent. (issue #11084)
diff --git a/src/testdir/test_textprop.vim b/src/testdir/test_textprop.vim
index 5167e8e..0a4037b 100644
--- a/src/testdir/test_textprop.vim
+++ b/src/testdir/test_textprop.vim
@@ -2892,6 +2892,22 @@
   call StopVimInTerminal(buf)
 endfunc
 
+func Test_prop_above_with_indent()
+  new
+  call setline(1, ['first line', '    second line', '    line below'])
+  setlocal cindent
+  call prop_type_add('indented', #{highlight: 'Search'})
+  call prop_add(3, 0, #{type: 'indented', text: 'here', text_align: 'above', text_padding_left: 4})
+  call assert_equal('    line below', getline(3))
+
+  exe "normal 3G2|a\<CR>"
+  call assert_equal('  ', getline(3))
+  call assert_equal('    line below', getline(4))
+
+  bwipe!
+  call prop_type_delete('indented')
+endfunc
+
 func Test_props_with_text_override()
   CheckRunVimInTerminal