Add GNU chsh option completions.

CHANGES

@@ -24,7 +24,7 @@ bash-completion (2.x)
   * Apply cardctl completion to pccardctl too.
   * Apply pine completion to alpine too.
   * Remove many unnecessary short option completions where long ones exist.
-  * Improve configure, cvs, gkrellm, lftp, mdadm, modprobe, mplayer,
+  * Improve chsh, configure, cvs, gkrellm, lftp, mdadm, modprobe, mplayer,
     mysqladmin, rsync, screen, service, scp, ssh, update-alternatives,
     vncviewer, and general hostname completions.
   * Add abook and wtf completion, based on work by Raphaël Droz.

contrib/chsh

@@ -8,8 +8,19 @@ _chsh()
     cur=`_get_cword`
     prev=${COMP_WORDS[COMP_CWORD-1]}
 
-    if [ "$prev" = "-s" ]; then
-        _shells
+    case "$prev" in
+        --list-shells|--help|-v|--version)
+            return 0
+            ;;
+        -s|--shell)
+            _shells
+            return 0
+            ;;
+    esac
+
+    if [[ "$cur" == -* && "$( uname -s )" == @(Linux|GNU|GNU/*) ]]; then
+        COMPREPLY=( $( compgen -W '--shell --list-shells --help --version' \
+            -- "$cur" ) )
     else
         COMPREPLY=( $( compgen -u -- "$cur" ) )
     fi