Fix compile error

[inq]

Motivation

I am trying to compile the master branch, but it looks to be broken by #528

I found that this is caused by a missing import.

Solution

So I imported the..

use std::sync::Arc;

Thanks! Happy new year!

[inkyu-prestolabs]

#822 will resolve the travis failure.

[tobz]

Thanks for the PR! We've already merged a fix for the error you found, but appreciate you submitting a PR nonetheless. :)

[inq]

Okay. Thank you!