~/trunk/src/scripts $ cros_workon --board=${BOARD} list --all
usage: cros_workon [-h]
                   [--log-level {fatal,critical,error,warning,notice,info,debug}]
                   [--log_format LOG_FORMAT] [--debug] [--nocolor]
                   [--board BOARD] [--host] [--remote REMOTE]
                   [--revision REVISION] [--command ITERATE_COMMAND]
                   [--workon_only] [--all]
                   {start,stop,info,list,list-all,iterate} ...
cros_workon: error: unrecognized arguments: --all

This version works:
cros_workon --all --board=${BOARD} list

I guess the requirement is to have --all before the list, but it's a regression.