New comment by Piraty on void-packages repository

https://github.com/void-linux/void-packages/pull/21039#issuecomment-616123715

Comment:
I did a local build (rebased 3f842d996a1bcd098217b857d4ef1c4a97118139 onto 828b33121c23730a58871d64f1dd4fcd2b92296a) and even got a different error.
Maybe it's racy?
```
=> zeroinstall-2.16_1: running do_build ...
dune build --root=. --profile=release @install
dune runtest --root=. --profile=release
Error: Error: mkdir: _build/default/.dune: File exists
make: *** [Makefile:65: test] Error 1
make: *** Waiting for unfinished jobs....
```