improved override header handling

[jeevatkm]

Supersedes PR #121

[codecov]

Codecov Report

Merging #125 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #125      +/-   ##
==========================================
+ Coverage   96.33%   96.33%   +<.01%     
==========================================
  Files          10       10              
  Lines        1037     1038       +1     
==========================================
+ Hits          999     1000       +1     
  Misses         21       21              
  Partials       17       17

Impacted Files	Coverage Δ
middleware.go	92.23% <100%> (+0.03%)	⬆️

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