prevention of overwrite to project_root

I fail to build. If, is including the word "td-agent" in the path.

e.g. 

`Omnibus::Config.project_root` is `/home/vagrant/omnibus-td-agent`

1. build for `my-agent`

```
bin/omnibus build my-agent
```

2. File is copied to another build path（`/home/vagrant/omnibus-my-agent`）

```
/home/vagrant/omnibus-my-agent/package-scripts/my-agent/postun
/home/vagrant/omnibus-my-agent/package-scripts/my-agent/preun
/home/vagrant/omnibus-my-agent/resources/my-agent/etc/init.d/my-agent
・
・
・
```

I want to not overwrite the project_root.