fix E741 on test_process_build

[tardyp]

recent pep8 does not like l (the letter) as a variable because some fonts make it undistinguishable from 1 (the number).

[mention-bot]

@tardyp, thanks for your PR! By analyzing the history of the files in this pull request, we identified @hborkhuis, @mozbhearsum and @rutsky to be potential reviewers.

[codecov]

Codecov Report

Merging #3107 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3107   +/-   ##
=======================================
  Coverage   88.29%   88.29%           
=======================================
  Files         314      314           
  Lines       32927    32927           
=======================================
  Hits        29072    29072           
  Misses       3855     3855

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[seankelly]

Is this the only usage of l?

Grepping the source and I see references all over the codebase. I wonder why this file is the only spot that needs fixing.

[tardyp]

@seankelly no, its just that I worked on this file as part of #3103 and my editor pointed a bunch of pep8 errors. I then did feel like putting that patch in #3103

I feel like fixing the whole codebase is much annoying job, and I would prefer to fix it part by part.