Fix typo

[martencassel]

Fix typo: variables

[GordonTheTurtle]

Please sign your commits following these rules:
https://github.com/moby/moby/blob/master/CONTRIBUTING.md#sign-your-work
The easiest way to do this is to amend the last commit:

$ git clone -b "patch-1" git@github.com:martencassel/infrakit.git somewhere
$ cd somewhere
$ git commit --amend -s --no-edit
$ git push -f

Amending updates the existing PR. You DO NOT need to open a new one.

[codecov]

Codecov Report

Merging #907 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #907   +/-   ##
=======================================
  Coverage   48.42%   48.42%           
=======================================
  Files          84       84           
  Lines        7859     7859           
=======================================
  Hits         3806     3806           
  Misses       3743     3743           
  Partials      310      310

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[thebsdbox]

LGTM, thanks for the fix