Capistrano：退出角色＆＃39;块

Question

此任务有效：

before :publishing, :execute do
  exit
end

但这不是：

before :publishing, :execute do
  on roles(:web) do
    exit
  end
end

它说的是：

(Backtrace restricted to imported tasks)
cap aborted!
SSHKit::Runner::ExecuteError: Exception while executing as deployer@XXX.XXX.XXX.XXX: exit

SystemExit: exit

Tasks: TOP => deploy:publishing => deploy:execute
(See full trace by running task with --trace)
The deploy has failed with an error: Exception while executing as deployer@XXX.XXX.XXX.XXX: exit

我需要在on roles(:web)块内运行exit（因为系统退出基于假设和条件）。

我该如何解决这个问题？

由于