patch 8.1.0539: cannot build without the sandbox
Problem: Cannot build without the sandbox.
Solution: Set the secure option instead of using the sandbox. Also restrict
the characters from 'spelllang' that are used for LANG.vim.
(suggested by Yasuhiro Matsumoto)
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index e57de8f..8a106e1 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -7339,7 +7339,7 @@
After this option has been set successfully, Vim will source the files
"spell/LANG.vim" in 'runtimepath'. "LANG" is the value of 'spelllang'
- up to the first comma, dot or underscore.
+ up to the first character that is not an ASCII letter and not a dash.
Also see |set-spc-auto|.