Releases Modes parts incorrect?

```
rebar3 --version      
rebar 3.14.2+build.4941.ref239df4f6 on Erlang/OTP 23 Erts 11.1.5
```

It seems that when I use `as prod` is not automatically use prod mode. And override options with ```[
  {mode, prod},
  {debug_info, keep}
]``` is not working. 
