Fix _filedir on bash 4.

We don't need to double-quote things for compgen w/ bash 4. Just putting
each file in double quotes is sufficient.

See: http://lists.gnu.org/archive/html/bug-bash/2009-03/msg00155.html

bash_completion

@@ -209,6 +209,12 @@ quote()
 # results in the original argument
 quote_readline()
 {
+	if [[ "${BASH_VERSINFO[0]}" -ge 4 ]] ; then
+		# This function isn't really necessary on bash 4
+		# See: http://lists.gnu.org/archive/html/bug-bash/2009-03/msg00155.html
+		echo "${1}"
+		return
+	fi
 	local t="${1//\\/\\\\}"
 	echo \'${t//\'/\'\\\'\'}\' #'# Help vim syntax highlighting
 }