DUB cannot fetch packages on Linux

[Kirill]

Whenever DUB tries to fetch a package, it returns the following:

```D
Package bindbc-glfw not found for registry at 
https://code.dlang.org/ (fallback ["registry at 
http://code.dlang.org/", "registry at 
https://code-mirror.dlang.io/", "registry at 
https://code-mirror2.dlang.io/", "registry at 
https://dub-registry.herokuapp.com/"]): HTTP request returned 
status code 503 (Service Unavailable)
```

Is it linux-specific? Do you have any ideas what might be the 
problem here?