Error: only one main allowed. Previously found main at *

[Brian via Digitalmars-d]

dmd latest version bug?

```sh
source/bootstrap.d(4,6): Error: only one main allowed. Previously 
found main at 
/tmp/dub_test_root-ad0fb2e3-6be1-4ca8-9153-e4fdd5c1b191.d(10,12)
dmd failed with exit code 1.
```
Build logs:
https://travis-ci.org/huntlabs/hunt-skeleton/jobs/389884419#L480