renew() should return the function result code of issue()
Thanks for you fix. I just merged it.
An suggestion: If you want to do something after a success renewal, you can use the "Le_ReloadCmd" option.
In which you can write any valid bash command, that will be executed after renewal.
currently the renew function does always return 0 even when the cert issuing failed. for now just return the function return code of issue().
maybe an additional offset (like +100) should be added to distinguish the issue error codes from the renew error codes.