fix(invoke-rc.d): fix a bug of generating existing words

In the current implementation, we try to filter out the elements of
"${options[@]}" that already appear in "${words[@]}".  The strategy is
to generate

a. "${options[@]}" and
b. the intersect of "${words[@]}" and "${options[@]}"

in a single list and to pick up only unique elements.  However, the
current implementation does not correctly generate "b. the intersect".
It also contains elements of words that contain any of "${options[@]}"
as a substring.  This possibly results in generating some words in the
command line as options.

scop#1564 (comment)

In this patch, we rather implement the filtering using `_compgen -X`.

Author: akinomyoga

completions-core/invoke-rc.d.bash

@@ -18,13 +18,10 @@ _comp_cmd_invoke_rc_d()
     if [[ $cword -eq 1 || $prev == --* ]]; then
         # generate valid_options
         local IFS='|'
-        local regex_options="${options[*]}"
-        IFS=$' \t\n'
-        _comp_compgen_split -- "$(
-            tr " " "\n" <<<"${words[*]} ${options[*]}" |
-                command grep -E -e "$regex_options" |
-                sort | uniq -u
-        )"
+        local exclude="@(${words[*]})"
+        _comp_unlocal IFS
+        _comp_compgen -- -W '"${options[@]}"' -X "$exclude"
+
         _comp_expand_glob services '"$sysvdir"/!(README*|*.sh|$_comp_backup_glob)' &&
             _comp_compgen -a -- -W '"${services[@]#"$sysvdir"/}"'
     elif [[ -x $sysvdir/$prev ]]; then