VM is not built with 'gorge' support
```
debian 9/stretch
choosenim devel
clone nimforum
```

```
root@debian:~/github.com/nim-lang/nimforum# nim -v                                                       
Nim Compiler Version 0.18.1 [Linux: amd64]                                                               
Compiled at 2018-06-22                                                                                   
Copyright (c) 2006-2018 by Andreas Rumpf                                                                 
                                                                                                         
active boot switches: -d:release
```

```
nimble backend
...
 Installing sass@#649e0701fa5c                                                                           
Downloading https://github.com/dom96/sass using git                                                      
Error: unhandled exception: VM is not built with 'gorge' support [ERecoverableError]                     
stack trace: (most recent call last)                                                                     
root/github.com/nim-lang/nimforum/nimforum.nimble(29) backendTask                                        
root/.choosenim/toolchains/nim-#devel/lib/system/nimscript.nim(237) exec                                 
root/.choosenim/toolchains/nim-#devel/lib/system/nimscript.nim(237, 7) Error: unhandled exception: FAILED: nimble c src/forum.nim

```