Fixed "service" completion, thanks to John Hedges (Debian: #586210)

The patch makes it safe even when every file in /etc/init.d/*
  has a proper completion (unlikely, but seems like it happened).

  Thanks to John Hedges <john@drystone.co.uk> for the patch, slightly
  modified to make it more compact.

CHANGES

@@ -1,7 +1,7 @@
 bash-completion (2.x)
 
   [ David Paleino ]
-  * Start work on 2.0
+  * Fixed "service" completion, thanks to John Hedges (Debian: #586210)
 
   [ Ville Skyttä ]
   * Activate hping2 completion also for hping and hping3.

contrib/service

@@ -32,9 +32,10 @@ _service()
     return 0
 } &&
 complete -F _service service
-[ -d /etc/init.d/ ] && complete -F _service -o default \
-    $(for i in /etc/init.d/*; do
-    complete -p ${i##*/} &>/dev/null || printf '%s\n' ${i##*/}; done)
+[ -d /etc/init.d/ ] && (
+    services=$(for i in /etc/init.d/*; do
+        complete -p ${i##*/} &>/dev/null || printf '%s\n' ${i##*/}; done)
+    [ -n "$services" ] && complete -F _service -o default $services;)
 
 # Local variables:
 # mode: shell-script