fix linter issue causing travis build failures (fix #1514)

[harshanarayana]

Fix #1514

[codecov]

Codecov Report

Merging #1515 into master will decrease coverage by 0.05%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master   #1515      +/-   ##
=========================================
- Coverage   91.45%   91.4%   -0.06%     
=========================================
  Files          18      18              
  Lines        1791    1791              
  Branches      339     339              
=========================================
- Hits         1638    1637       -1     
  Misses        130     130              
- Partials       23      24       +1

Impacted Files	Coverage Δ
sanic/testing.py	95.29% <100%> (ø)	⬆️
sanic/router.py	95.43% <0%> (-0.46%)	⬇️

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