Now release_name may change

in config/deploy.rb set custom release name

```
set :release_name, "#{fetch(:branch)}"
```

on server see
```
$ ls releases/
develop  release_39.08	release_39.09
$ ls -la current
lrwxrwxrwx 1 www-data www-data 36 Mar 23 14:29 current -> /..../releases/release_39.08
```