feat(_comp_compgen_known_hosts): return 2 on usage error

Author: akinomyoga

bash_completion

@@ -2421,7 +2421,7 @@ _comp_compgen_known_hosts__impl()
             F)
                 if [[ ! $OPTARG ]]; then
                     echo "bash_completion: $FUNCNAME: -F: an empty filename is specified" >&2
-                    return 1
+                    return 2
                 fi
                 configfile=$OPTARG
                 ;;
@@ -2430,13 +2430,13 @@ _comp_compgen_known_hosts__impl()
             6) ipv6=set ;;
             *)
                 echo "bash_completion: $FUNCNAME: usage error" >&2
-                return 1
+                return 2
                 ;;
         esac
     done
     if (($# < OPTIND)); then
         echo "bash_completion: $FUNCNAME: missing mandatory argument CWORD" >&2
-        return 1
+        return 2
     fi
     cur=${!OPTIND}
     ((OPTIND += 1))
@@ -2446,7 +2446,7 @@ _comp_compgen_known_hosts__impl()
                 printf '%s ' ${!OPTIND}
                 shift
             done)" >&2
-        return 1
+        return 2
     fi
 
     [[ $cur == *@* ]] && prefix=$prefix${cur%@*}@ && cur=${cur#*@}