latest Nimble hangs on Windows 10
Hi,
I installed Nim from the Github devel repository and Nimble with:
```sh
koch nimble
```
Then tried installing a package on Windows 10 using:
```sh
nimble install 'package_name'
```
This crashes the *Windows Command Prompt* but **nimble.exe** still remains active (is still visible in the task manager).
It seems to install the package and dependencies correctly. Below is a screenshot at the moment just before it crashed:
![nimble_screenshot](https://user-images.githubusercontent.com/10289651/31249287-139bb7d0-aa17-11e7-997d-47053a403c69.png)

Specs:
- Windows 10
- Nim Compiler Version 0.17.3 (2017-10-05) [Windows: i386]
- MinGW GCC 7.10 (gcc (i686-win32-sjlj-rev2, Built by MinGW-W64 project) 7.1.0)

Any ideas?