Update gitlab-grack to 2.0.1 to get unicorn to stop creating zombies.

Addresses #1461 (closed) and private issue https://dev.gitlab.org/gitlab/gitlabhq/issues/2253.

This regression was introduced between 7.9 and the 7.10 rcs, so no changelog item for 7.10 proper.

cc @JobV @jacobvosmaer

mentioned in issue #1438 (closed)

Status changed to merged

mentioned in commit eca214a6

So this should go to RC5

@dzaporozhets that would be great.

@jacobvosmaer good job on the meme!

mentioned in commit adcc2049