wtf: Don't offer -f if it was already specified.

Submitted-by: Raphaël Droz (modified)
http://lists.alioth.debian.org/pipermail/bash-completion-devel/2013-November/004991.html

completions/wtf

@@ -3,11 +3,15 @@
 
 _wtf()
 {
-    local cur prev words cword
+    local cur prev words cword addf
     _init_completion || return
 
     [[ $prev == -f ]] && _filedir && return 0
-    [[ $cur == -* ]] && COMPREPLY=( -f ) && return 0
+    [[ ${words[@]} == *\ -f* ]] && addf= || addf=-f
+    if [[ $cur == -* ]]; then
+        COMPREPLY=( $addf )
+        return 0
+    fi
 
     local db
 
@@ -20,7 +24,7 @@ _wtf()
     done
     [[ -z $db ]] && db=${ACRONYMDB:-/usr/share/misc/acronyms*}
 
-    COMPREPLY=( $( compgen -W "$( cut -f 1 -s $db 2>/dev/null ) -f" \
+    COMPREPLY=( $( compgen -W "$( cut -f 1 -s $db 2>/dev/null ) $addf" \
         -- "${cur^^}" ) )
 } &&
 complete -F _wtf wtf