Clean up code and tighten flake8 linting

[cyberw]

No description provided.

[codecov]

Codecov Report

Merging #1558 into master will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1558      +/-   ##
==========================================
+ Coverage   82.27%   82.30%   +0.02%     
==========================================
  Files          28       28              
  Lines        2567     2565       -2     
  Branches      392      392              
==========================================
- Hits         2112     2111       -1     
  Misses        356      356              
+ Partials       99       98       -1     

Impacted Files	Coverage Δ
locust/__init__.py	100.00% <100.00%> (ø)
locust/clients.py	95.09% <100.00%> (ø)
locust/contrib/fasthttp.py	86.85% <100.00%> (+0.93%)	⬆️
locust/main.py	20.26% <100.00%> (-0.70%)	⬇️
locust/runners.py	82.54% <0.00%> (-0.19%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update c42c227...ffef2bf. Read the comment docs.