bash-completion: fix completion of complete verbs

When doing 'command verb<TAB>', the arguments for verb would be
proposed, but it is too early. We should complete verb first.

https://bugs.freedesktop.org/show_bug.cgi?id=74596

shell-completion/bash/hostnamectl

@@ -41,7 +41,7 @@ _hostnamectl() {
                       [NAME]='set-hostname'
         )
 
-        for ((i=0; i <= COMP_CWORD; i++)); do
+        for ((i=0; i < COMP_CWORD; i++)); do
                 if __contains_word "${COMP_WORDS[i]}" ${VERBS[*]}; then
                         verb=${COMP_WORDS[i]}
                         break