Remove unused symbols

[codecov-io]

Codecov Report

Merging #109 into master will decrease coverage by 0.07%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #109      +/-   ##
==========================================
- Coverage   85.78%   85.71%   -0.08%     
==========================================
  Files           1        1              
  Lines         190      189       -1     
  Branches       11       11              
==========================================
- Hits          163      162       -1     
  Misses         18       18              
  Partials        9        9

Impacted Files	Coverage Δ
src/cider/piggieback.clj	85.71% <100%> (-0.08%)	:arrow_down:

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[bbatsov]

Thanks!