Fix Sanic.url_for method

[myusko]

This is PR fixed #1420 issue.

[codecov]

Codecov Report

Merging #1574 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1574      +/-   ##
==========================================
- Coverage   91.35%   91.34%   -0.01%     
==========================================
  Files          18       18              
  Lines        1828     1826       -2     
  Branches      351      350       -1     
==========================================
- Hits         1670     1668       -2     
  Misses        132      132              
  Partials       26       26

Impacted Files	Coverage Δ
sanic/app.py	92.45% <ø> (-0.04%)	⬇️

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[ahopkins]

See #1591

[ahopkins]

Is this still necessary?