Move brg $output before setting from $client

When running brg with -c, the following error would always be displayed:

ERROR: Specify -c or -o, not both.

This was because $output was being set from $client before the check
rather than after. Reordering corrected this.
Added noop to debian brg for list_release

list_release was defined with an empty body, which is not valid in POSIX
shell, thus causing any brg command including debian to fail. Added a
noop (":") for now.